# Settings

The Scrapy settings allows you to customize the behaviour of all Scrapy components, including the core, extensions, pipelines and spiders themselves.

The infrastructure of the settings provides a global namespace of key-value mappings that the code can use to pull configuration values from. The settings can be populated through different mechanisms, which are described below.

The settings are also the mechanism for selecting the currently active Scrapy project (in case you have many).

For a list of available built-in settings see: Built-in settings reference.

## Designating the settings

When you use Scrapy, you have to tell it which settings you’re using. You can do this by using an environment variable, `SCRAPY_SETTINGS_MODULE`.

The value of `SCRAPY_SETTINGS_MODULE` should be in Python path syntax, e.g. `myproject.settings`. Note that the settings module should be on the Python import search path.

## Populating the settings

Settings can be populated using different mechanisms, each of which has a different precedence:

> 1. Command-line settings (highest precedence)

> 2. Spider settings

> 3. Project settings

> 4. Add-on settings

> 5. Command-specific default settings

> 6. Global default settings (lowest precedence)

### 1. Command-line settings

Settings set in the command line have the highest precedence, overriding any other settings.

You can explicitly override one or more settings using the `-s` (or `--set`) command-line option.

Example:

    scrapy crawl myspider -s LOG_LEVEL=INFO -s LOG_FILE=scrapy.log

### 2. Spider settings

Spiders can define their own settings that will take precedence and override the project ones.

Note

Pre-crawler settings cannot be defined per spider, and reactor settings should not have a different value per spider when running multiple spiders in the same process.

One way to do so is by setting their `custom_settings` attribute:

    import scrapy

    class MySpider(scrapy.Spider):
        name = "myspider"

        custom_settings = {
            "SOME_SETTING": "some value",
        }

It’s often better to implement `update_settings()` instead, and settings set there should use the `"spider"` priority explicitly:

    import scrapy

    class MySpider(scrapy.Spider):
        name = "myspider"

        @classmethod
        def update_settings(cls, settings):
            super().update_settings(settings)
            settings.set("SOME_SETTING", "some value", priority="spider")

Added in version 2.11.

It’s also possible to modify the settings in the `from_crawler()` method, e.g. based on spider arguments or other logic:

    import scrapy

    class MySpider(scrapy.Spider):
        name = "myspider"

        @classmethod
        def from_crawler(cls, crawler, *args, **kwargs):
            spider = super().from_crawler(crawler, *args, **kwargs)
            if "some_argument" in kwargs:
                spider.settings.set(
                    "SOME_SETTING", kwargs["some_argument"], priority="spider"
                )
            return spider

### 3. Project settings

Scrapy projects include a settings module, usually a file called `settings.py`, where you should populate most settings that apply to all your spiders.

See also

Designating the settings

### 4. Add-on settings

Add-ons can modify settings. They should do this with `"addon"` priority where possible.

### 5. Command-specific default settings

Each Scrapy command can have its own default settings, which override the global default settings.

Those command-specific default settings are specified in the `default_settings` attribute of each command class.

### 6. Default global settings

The `scrapy.settings.default_settings` module defines global default values for some built-in settings.

Note

`startproject` generates a `settings.py` file that sets some settings to different values.

The reference documentation of settings indicates the default value if one exists. If `startproject` sets a value, that value is documented as default, and the value from `scrapy.settings.default_settings` is documented as “fallback”.

## Compatibility with pickle

Setting values must be picklable.

## Import paths and classes

When a setting references a callable object to be imported by Scrapy, such as a class or a function, there are two different ways you can specify that object:

- As a string containing the import path of that object

- As the object itself

For example:

    from mybot.pipelines.validate import ValidateMyItem

    ITEM_PIPELINES = {
        # passing the classname...
        ValidateMyItem: 300,
        # ...equals passing the class path
        "mybot.pipelines.validate.ValidateMyItem": 300,
    }

Note

Passing non-callable objects is not supported.

## How to access settings

In a spider, settings are available through `self.settings`:

    class MySpider(scrapy.Spider):
        name = "myspider"
        start_urls = ["http://example.com"]

        def parse(self, response):
            print(f"Existing settings: {self.settings.attributes.keys()}")

Note

The `settings` attribute is set in the base Spider class after the spider is initialized. If you want to use settings before the initialization (e.g., in your spider’s `__init__()` method), you’ll need to override the `from_crawler()` method.

Components can also access settings.

The `settings` object can be used like a `dict` (e.g. `settings["LOG_ENABLED"]`). However, to support non-string setting values, which may be passed from the command line as strings, it is recommended to use one of the methods provided by the `Settings` API.

## Component priority dictionaries

A component priority dictionary is a `dict` where keys are components and values are component priorities. For example:

    {
        "path.to.ComponentA": None,
        ComponentB: 100,
    }

A component can be specified either as a class object or through an import path.

Warning

Component priority dictionaries are regular `dict` objects. Be careful not to define the same component more than once, e.g. with different import path strings or defining both an import path and a `type` object.

A priority can be an `int` or `None`.

A component with priority 1 goes before a component with priority 2. What going before entails, however, depends on the corresponding setting. For example, in the `DOWNLOADER_MIDDLEWARES` setting, components have their `process_request()` method executed before that of later components, but have their `process_response()` method executed after that of later components.

A component with priority `None` is disabled.

Some component priority dictionaries get merged with some built-in value. For example, `DOWNLOADER_MIDDLEWARES` is merged with `DOWNLOADER_MIDDLEWARES_BASE`. This is where `None` comes in handy, allowing you to disable a component from the base setting in the regular setting:

    DOWNLOADER_MIDDLEWARES = {
        "scrapy.downloadermiddlewares.offsite.OffsiteMiddleware": None,
    }

## Special settings

The following settings work slightly differently than all other settings.

### Pre-crawler settings

Pre-crawler settings are settings used before the `Crawler` object is created.

These settings cannot be set from a spider.

These settings are:

- `TWISTED_REACTOR_ENABLED`

- `SPIDER_LOADER_CLASS` and settings used by the corresponding spider loader class, e.g. `SPIDER_MODULES` and `SPIDER_LOADER_WARN_ONLY` for the default spider loader class.

### Reactor settings

Reactor settings are settings tied to the Twisted reactor.

These settings can be defined from a spider. However, because only 1 reactor can be used per process, these settings cannot use a different value per spider when running multiple spiders in the same process.

In general, if different spiders define different values, the first defined value is used. However, if two spiders request a different reactor, an exception is raised.

These settings are:

- `ASYNCIO_EVENT_LOOP` (not possible to set per-spider when using `AsyncCrawlerProcess`, see below)

- `TWISTED_DNS_RESOLVER` and settings used by the corresponding component, e.g. `DNSCACHE_ENABLED`, `DNSCACHE_SIZE` and `DNS_TIMEOUT` for the default one.

- `REACTOR_THREADPOOL_MAXSIZE`

- `TWISTED_REACTOR` (ignored when using `AsyncCrawlerProcess`, see below)

`ASYNCIO_EVENT_LOOP` and `TWISTED_REACTOR` are used upon installing the reactor. The rest of the settings are applied when starting the reactor.

There is an additional restriction for `TWISTED_REACTOR` and `ASYNCIO_EVENT_LOOP` when using `AsyncCrawlerProcess`: when this class is instantiated, it installs `AsyncioSelectorReactor`, ignoring the value of `TWISTED_REACTOR` and using the value of `ASYNCIO_EVENT_LOOP` that was passed to `AsyncCrawlerProcess.__init__()`. If a different value for `TWISTED_REACTOR` or `ASYNCIO_EVENT_LOOP` is provided later, e.g. in per-spider settings, an exception will be raised.

All of these settings, except for `ASYNCIO_EVENT_LOOP`, are only used when the Twisted reactor is used, i.e. when `TWISTED_REACTOR_ENABLED` is `True`.

### Logging settings

Logging settings are settings that configure the global root logging handler installed by `configure_logging()`.

These settings can be defined from a spider. However, because only 1 root logging handler is active per process, these settings cannot use a different value per spider when running multiple spiders in the same process.

These settings are:

- `LOG_DATEFORMAT`

- `LOG_ENABLED`

- `LOG_ENCODING`

- `LOG_FILE`

- `LOG_FILE_APPEND`

- `LOG_FORMAT`

- `LOG_LEVEL`

- `LOG_SHORT_NAMES`

- `LOG_STDOUT`

## Built-in settings reference

Here’s a list of all available Scrapy settings, in alphabetical order, along with their default values and the scope where they apply.

The scope, where available, shows where the setting is being used, if it’s tied to any particular component. In that case the module of that component will be shown, typically an extension, middleware or pipeline. It also means that the component must be enabled in order for the setting to have any effect.

### ADDONS

Default: `{}`

A dict containing paths to the add-ons enabled in your project and their priorities. For more information, see Add-ons.

### AWS_ACCESS_KEY_ID

Default: `None`

The AWS access key used by code that requires access to Amazon Web services, such as the S3 feed storage backend.

### AWS_SECRET_ACCESS_KEY

Default: `None`

The AWS secret key used by code that requires access to Amazon Web services, such as the S3 feed storage backend.

### AWS_SESSION_TOKEN

Default: `None`

The AWS security token used by code that requires access to Amazon Web services, such as the S3 feed storage backend, when using temporary security credentials.

### AWS_ENDPOINT_URL

Default: `None`

Endpoint URL used for S3-like storage, for example Minio or s3.scality.

### AWS_USE_SSL

Default: `None`

Use this option if you want to disable SSL connection for communication with S3 or S3-like storage. By default SSL will be used.

### AWS_VERIFY

Default: `None`

Verify SSL connection between Scrapy and S3 or S3-like storage. By default SSL verification will occur.

### AWS_REGION_NAME

Default: `None`

The name of the region associated with the AWS client.

### ASYNCIO_EVENT_LOOP

Default: `None`

Import path of a given `asyncio` event loop class.

If the asyncio reactor is enabled (see `TWISTED_REACTOR`) this setting can be used to specify the asyncio event loop to be used with it. Set the setting to the import path of the desired asyncio event loop class. If the setting is set to `None` the default asyncio event loop will be used.

If you are installing the asyncio reactor manually using the `install_reactor()` function, you can use the `event_loop_path` parameter to indicate the import path of the event loop class to be used.

Note that the event loop class must inherit from `asyncio.AbstractEventLoop`.

Caution

Please be aware that, when using a non-default event loop (either defined via `ASYNCIO_EVENT_LOOP` or installed with `install_reactor()`), Scrapy will call `asyncio.set_event_loop()`, which will set the specified event loop as the current loop for the current OS thread.

Note

This is a reactor setting.

### BOT_NAME

Default: `<project name>` (fallback: `'scrapybot'`)

The name of the bot implemented by this Scrapy project (also known as the project name). This name will be used for the logging too.

It’s automatically populated with your project name when you create your project with the `startproject` command.

### CONCURRENT_ITEMS

Default: `100`

Maximum number of concurrent items (per response) to process in parallel in item pipelines.

### CONCURRENT_REQUESTS

Default: `16`

The maximum number of concurrent (i.e. simultaneous) requests that will be performed by the Scrapy downloader.

### CONCURRENT_REQUESTS_PER_DOMAIN

Default: `1` (fallback: `8`)

The maximum number of concurrent (i.e. simultaneous) requests that will be performed to any single domain.

See also: AutoThrottle extension and its `AUTOTHROTTLE_TARGET_CONCURRENCY` option.

### DEFAULT_DROPITEM_LOG_LEVEL

Default: `"WARNING"`

Default log level of messages about dropped items.

When an item is dropped by raising `scrapy.exceptions.DropItem` from the `process_item()` method of an item pipeline, a message is logged, and by default its log level is the one configured in this setting.

You may specify this log level as an integer (e.g. `20`), as a log level constant (e.g. `logging.INFO`) or as a string with the name of a log level constant (e.g. `"INFO"`).

When writing an item pipeline, you can force a different log level by setting `scrapy.exceptions.DropItem.log_level` in your `scrapy.exceptions.DropItem` exception. For example:

    from scrapy.exceptions import DropItem

    class MyPipeline:
        def process_item(self, item):
            if not item.get("price"):
                raise DropItem("Missing price data", log_level="INFO")
            return item

### DEFAULT_ITEM_CLASS

Default: `'scrapy.Item'`

The default class that will be used for instantiating items in the the Scrapy shell.

### DEFAULT_REQUEST_HEADERS

Default:

    {
        "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
        "Accept-Language": "en",
    }

The default headers used for Scrapy HTTP Requests. They’re populated in the `DefaultHeadersMiddleware`.

Caution

Cookies set via the `Cookie` header are not considered by the CookiesMiddleware. If you need to set cookies for a request, use the `Request.cookies` parameter. This is a known current limitation that is being worked on.

### DEPTH_LIMIT

Default: `0`

Scope: `scrapy.spidermiddlewares.depth.DepthMiddleware`

The maximum depth that will be allowed to crawl for any site. If zero, no limit will be imposed.

### DEPTH_PRIORITY

Default: `0`

Scope: `scrapy.spidermiddlewares.depth.DepthMiddleware`

An integer that is used to adjust the `priority` of a `Request` based on its depth.

The priority of a request is adjusted as follows:

    request.priority = request.priority - (depth * DEPTH_PRIORITY)

As depth increases, positive values of `DEPTH_PRIORITY` decrease request priority (BFO), while negative values increase request priority (DFO). See also Does Scrapy crawl in breadth-first or depth-first order?.

Note

This setting adjusts priority in the opposite way compared to other priority settings `REDIRECT_PRIORITY_ADJUST` and `RETRY_PRIORITY_ADJUST`.

### DEPTH_STATS_VERBOSE

Default: `False`

Scope: `scrapy.spidermiddlewares.depth.DepthMiddleware`

Whether to collect verbose depth stats. If this is enabled, the number of requests for each depth is collected in the stats.

### DNSCACHE_ENABLED

Default: `True`

Whether to enable DNS in-memory cache.

Note

This setting is only used by `CachingThreadedResolver` and `CachingHostnameResolver`. It has no effect when `TWISTED_REACTOR_ENABLED` is `False`, and may have no effect either when `DNS_RESOLVER` is set to a different resolver.

Note

This is a reactor setting.

### DNSCACHE_SIZE

Default: `10000`

DNS in-memory cache size, see `DNSCACHE_ENABLED`.

Note

This is a reactor setting.

### TWISTED_DNS_RESOLVER

Default: `'scrapy.resolver.CachingThreadedResolver'`

The class to be used by Twisted to resolve DNS names. The default `scrapy.resolver.CachingThreadedResolver` supports specifying a timeout for DNS requests via the `DNS_TIMEOUT` setting, but works only with IPv4 addresses. Scrapy provides an alternative resolver, `scrapy.resolver.CachingHostnameResolver`, which supports IPv4/IPv6 addresses but does not take the `DNS_TIMEOUT` setting into account.

Note

This setting has no effect when `TWISTED_REACTOR_ENABLED` is `False`.

Note

This is a reactor setting.

### DNS_TIMEOUT

Default: `60`

Timeout for processing of DNS queries in seconds. Float is supported.

Note

This setting is only used by `CachingThreadedResolver`. It has no effect when `TWISTED_REACTOR_ENABLED` is `False`, and may have no effect either when `DNS_RESOLVER` is set to a different resolver.

Note

This is a reactor setting.

### DOWNLOADER

Default: `'scrapy.core.downloader.Downloader'`

The downloader to use for crawling.

### DOWNLOADER_CLIENT_TLS_CIPHERS

Default: `'DEFAULT'`

Use this setting to customize the TLS/SSL ciphers used by the HTTPS download handler.

The setting should contain a string in the OpenSSL cipher list format, these ciphers will be used as client ciphers. Changing this setting may be necessary to access certain HTTPS websites: for example, you may need to use `'DEFAULT:!DH'` for a website with weak DH parameters or enable a specific cipher that is not included in `DEFAULT` if a website requires it.

Set this setting to `None` to use the default ciphers of the underlying TLS implementation.

Changed in version 2.17.0: Added support for setting this to `None`.

Note

Handling of this setting needs to be implemented inside the download handler, so it’s not guaranteed to be supported by all 3rd-party handlers.

See also

Protocol versions and ciphers

### DOWNLOAD_TLS_MAX_VERSION

Added in version 2.17.0.

Default: `None`

Use this setting to change the maximum version of the TLS protocol allowed to be used by Scrapy.

This setting must be either `None`, in which case it doesn’t affect the version selection, or one of these string values:

- `'TLSv1.0'`

- `'TLSv1.1'`

- `'TLSv1.2'`

- `'TLSv1.3'`

The range of allowed TLS versions advertised by Scrapy when making TLS connections will depend on the TLS implementation defaults and the values of `DOWNLOAD_TLS_MIN_VERSION` and `DOWNLOAD_TLS_MAX_VERSION`. It’s possible to re-enable versions that are supported by the TLS implementation but disabled by default by adjusting these settings, but it’s impossible to enable unsupported ones, such as any versions below 1.2 in many modern environments.

Note

Handling of this setting needs to be implemented inside the download handler, so it’s not guaranteed to be supported by all 3rd-party handlers. Additionally, the set of supported TLS versions depends on the TLS implementation being used by the handler.

See also

Protocol versions and ciphers

### DOWNLOAD_TLS_MIN_VERSION

Added in version 2.17.0.

Default: `None`

Use this setting to change the minimum version of the TLS protocol allowed to be used by Scrapy.

See `DOWNLOAD_TLS_MAX_VERSION` for the details and limitations.

See also

Protocol versions and ciphers

### DOWNLOADER_CLIENT_TLS_VERBOSE_LOGGING

Default: `False`

Setting this to `True` will enable DEBUG level messages about TLS connection parameters after establishing HTTPS connections. The kind of information logged depends on the implementation of the download handler and the versions of the TLS-related libraries.

Note

Handling of this setting needs to be implemented inside the download handler, so it’s not guaranteed to be supported by all 3rd-party handlers.

### DOWNLOADER_MIDDLEWARES

Default: `{}`

A dict containing the downloader middlewares enabled in your project, and their orders. For more info see Activating a downloader middleware.

### DOWNLOADER_MIDDLEWARES_BASE

Default:

    {
        "scrapy.downloadermiddlewares.offsite.OffsiteMiddleware": 50,
        "scrapy.downloadermiddlewares.robotstxt.RobotsTxtMiddleware": 100,
        "scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware": 300,
        "scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware": 350,
        "scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware": 400,
        "scrapy.downloadermiddlewares.useragent.UserAgentMiddleware": 500,
        "scrapy.downloadermiddlewares.retry.RetryMiddleware": 550,
        "scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware": 580,
        "scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware": 590,
        "scrapy.downloadermiddlewares.redirect.RedirectMiddleware": 600,
        "scrapy.downloadermiddlewares.cookies.CookiesMiddleware": 700,
        "scrapy.downloadermiddlewares.httpproxy.HttpProxyMiddleware": 750,
        "scrapy.downloadermiddlewares.stats.DownloaderStats": 850,
        "scrapy.downloadermiddlewares.httpcache.HttpCacheMiddleware": 900,
    }

A dict containing the downloader middlewares enabled by default in Scrapy. Low orders are closer to the engine, high orders are closer to the downloader. You should never modify this setting in your project, modify `DOWNLOADER_MIDDLEWARES` instead. For more info see Activating a downloader middleware.

### DOWNLOADER_STATS

Default: `True`

Whether to enable downloader stats collection.

### DOWNLOAD_DELAY

Default: `1` (fallback: `0`)

Minimum seconds to wait between 2 consecutive requests to the same domain.

Use `DOWNLOAD_DELAY` to throttle your crawling speed, to avoid hitting servers too hard.

Decimal numbers are supported. For example, to send a maximum of 4 requests every 10 seconds:

    DOWNLOAD_DELAY = 2.5

This setting is also affected by the `RANDOMIZE_DOWNLOAD_DELAY` setting, which is enabled by default.

Note that `DOWNLOAD_DELAY` can lower the effective per-domain concurrency below `CONCURRENT_REQUESTS_PER_DOMAIN`. If the response time of a domain is lower than `DOWNLOAD_DELAY`, the effective concurrency for that domain is 1. When testing throttling configurations, it usually makes sense to lower `CONCURRENT_REQUESTS_PER_DOMAIN` first, and only increase `DOWNLOAD_DELAY` once `CONCURRENT_REQUESTS_PER_DOMAIN` is 1 but a higher throttling is desired.

Note

This delay can be set per spider using `download_delay` spider attribute.

It is also possible to change this setting per domain, although it requires non-trivial code. See the implementation of the AutoThrottle extension for an example.

### DOWNLOAD_BIND_ADDRESS

Default: `None`

The default local outgoing address for download-handler connections.

This setting can be either:

- a host address as a string (e.g. `"127.0.0.2"`), in which case the local port is chosen automatically, or

- a `(host, port)` tuple (e.g. `("127.0.0.2", 50000)`) to bind to both a specific local interface and a specific local port.

For example:

    # Bind to this local address
    DOWNLOAD_BIND_ADDRESS = "127.0.0.2"

    # Bind to this local address and local port
    DOWNLOAD_BIND_ADDRESS = ("127.0.0.2", 5000)

If set, built-in HTTP download handlers use this value by default. Set the `bindaddress` request meta key to override it for a specific request.

Note

Handling of this setting needs to be implemented inside the download handler, so it’s not guaranteed to be supported by all 3rd-party handlers. Specifying the port is unsupported by `HttpxDownloadHandler`.

### DOWNLOAD_HANDLERS

Default: `{}`

A dict containing the download handlers enabled in your project.

See `DOWNLOAD_HANDLERS_BASE` for example format.

See also

Unencrypted protocols and Local and non-network resources

### DOWNLOAD_HANDLERS_BASE

Default:

    {
        "data": "scrapy.core.downloader.handlers.datauri.DataURIDownloadHandler",
        "file": "scrapy.core.downloader.handlers.file.FileDownloadHandler",
        "http": "scrapy.core.downloader.handlers.http11.HTTP11DownloadHandler",
        "https": "scrapy.core.downloader.handlers.http11.HTTP11DownloadHandler",
        "s3": "scrapy.core.downloader.handlers.s3.S3DownloadHandler",
        "ftp": "scrapy.core.downloader.handlers.ftp.FTPDownloadHandler",
    }

(when `TWISTED_REACTOR_ENABLED` is `True`)

    {
        "data": "scrapy.core.downloader.handlers.datauri.DataURIDownloadHandler",
        "file": "scrapy.core.downloader.handlers.file.FileDownloadHandler",
        "http": "scrapy.core.downloader.handlers._httpx.HttpxDownloadHandler",
        "https": "scrapy.core.downloader.handlers._httpx.HttpxDownloadHandler",
        "s3": "scrapy.core.downloader.handlers.s3.S3DownloadHandler",
        "ftp": None,
    }

(when `TWISTED_REACTOR_ENABLED` is `False`)

A dict containing the download handlers enabled by default in Scrapy. You should never modify this setting in your project, modify `DOWNLOAD_HANDLERS` instead.

You can disable any of these download handlers by assigning `None` to their URI scheme in `DOWNLOAD_HANDLERS`. E.g., to disable the built-in FTP handler (without replacement), place this in your `settings.py`:

    DOWNLOAD_HANDLERS = {
        "ftp": None,
    }

See also

Unencrypted protocols and Local and non-network resources

### DOWNLOAD_SLOTS

Default: `{}`

Allows to define concurrency/delay parameters on per slot (domain) basis:

>     DOWNLOAD_SLOTS = {
>         "quotes.toscrape.com": {"concurrency": 1, "delay": 2, "randomize_delay": False},
>         "books.toscrape.com": {"delay": 3, "randomize_delay": False},
>     }

Note

For other downloader slots default settings values will be used:

- `DOWNLOAD_DELAY`: `delay`

- `CONCURRENT_REQUESTS_PER_DOMAIN`: `concurrency`

- `RANDOMIZE_DOWNLOAD_DELAY`: `randomize_delay`

### DOWNLOAD_TIMEOUT

Default: `180`

The amount of time (in secs) that the downloader will wait before timing out.

Note

This timeout can be per-request using the `download_timeout` `Request.meta` key.

Note

Handling of this setting needs to be implemented inside the download handler, so it’s not guaranteed to be supported by all 3rd-party handlers.

### DOWNLOAD_MAXSIZE

Default: `1073741824` (1 GiB)

The maximum response body size (in bytes) allowed. Bigger responses are aborted and ignored.

This applies both before and after compression. If decompressing a response body would exceed this limit, decompression is aborted and the response is ignored.

Use `0` to disable this limit.

Note

This limit can be set per-request using the `download_maxsize` `Request.meta` key.

Note

Checking responses before decompressing them needs to be implemented inside the download handler, so it’s not guaranteed to be supported by all 3rd-party handlers.

### DOWNLOAD_WARNSIZE

Default: `33554432` (32 MiB)

If the size of a response exceeds this value, before or after compression, a warning will be logged about it.

Use `0` to disable this limit.

Note

This limit can be set per-request using the `download_warnsize` `Request.meta` key.

Note

Checking responses before decompressing them needs to be implemented inside the download handler, so it’s not guaranteed to be supported by all 3rd-party handlers.

### DOWNLOAD_FAIL_ON_DATALOSS

Default: `True`

Whether or not to fail on broken responses, that is, when the declared `Content-Length` does not match content sent by the server or a chunked response was not properly finished. If `True`, these responses raise a `ResponseDataLossError` exception. If `False`, these responses are passed through and the flag `dataloss` is added to the response, i.e.: `'dataloss' in response.flags` is `True`.

Optionally, this can be set per-request basis by using the `download_fail_on_dataloss` Request.meta key to `False`.

Note

A broken response, or data loss error, may happen under several circumstances, from server misconfiguration to network errors to data corruption. It is up to the user to decide if it makes sense to process broken responses considering they may contain partial or incomplete content. If `RETRY_ENABLED` is `True` and this setting is set to `True`, the `ResponseDataLossError` failure will be retried as usual.

Note

Handling of this setting needs to be implemented inside the download handler, so it’s not guaranteed to be supported by all 3rd-party handlers.

Warning

This setting is ignored by the `H2DownloadHandler` download handler. In case of a data loss error, the corresponding HTTP/2 connection may be corrupted, affecting other requests that use the same connection; hence, a `ResponseFailed([InvalidBodyLengthError])` failure is always raised for every request that was using that connection.

### DOWNLOAD_VERIFY_CERTIFICATES

Default: `False`

Whether the HTTPS download handlers should verify the server TLS certificate when making a request and abort the request if the verification fails.

Note

Handling of this setting needs to be implemented inside the download handler, so it’s not guaranteed to be supported by all 3rd-party handlers. The exact behavior of a handler (e.g. whether certificate problems are logged when this setting is set to `False`) depends on its implementation.

See also

Certificate verification

### DUPEFILTER_CLASS

Default: `'scrapy.dupefilters.RFPDupeFilter'`

The class used to detect and filter duplicate requests.

The default, `RFPDupeFilter`, filters based on the `REQUEST_FINGERPRINTER_CLASS` setting.

To change how duplicates are checked, you can point `DUPEFILTER_CLASS` to a custom subclass of `RFPDupeFilter` that overrides its `__init__` method to use a different request fingerprinting class. For example:

    from scrapy.dupefilters import RFPDupeFilter
    from scrapy.utils.request import fingerprint

    class CustomRequestFingerprinter:
        def fingerprint(self, request):
            return fingerprint(request, include_headers=["X-ID"])

    class CustomDupeFilter(RFPDupeFilter):

        def __init__(self, path=None, debug=False, *, fingerprinter=None):
            super().__init__(
                path=path, debug=debug, fingerprinter=CustomRequestFingerprinter()
            )

To disable duplicate request filtering set `DUPEFILTER_CLASS` to `'scrapy.dupefilters.BaseDupeFilter'`. Note that not filtering out duplicate requests may cause crawling loops. It is usually better to set the `dont_filter` parameter to `True` on the `__init__` method of a specific `Request` object that should not be filtered out.

A class assigned to `DUPEFILTER_CLASS` must implement the following interface:

    class MyDupeFilter:

        @classmethod
        def from_crawler(cls, crawler):
            """Returns an instance of this duplicate request filtering class
            based on the current Crawler instance."""
            return cls()

        def request_seen(self, request):
            """Returns ``True`` if *request* is a duplicate of another request
            seen in a previous call to :meth:`request_seen`, or ``False``
            otherwise."""
            return False

        def open(self):
            """Called before the spider opens. It may return a deferred."""
            pass

        def close(self, reason):
            """Called before the spider closes. It may return a deferred."""
            pass

        def log(self, request, spider):
            """Logs that a request has been filtered out.

            It is called right after a call to :meth:`request_seen` that
            returns ``True``.

            If :meth:`request_seen` always returns ``False``, such as in the
            case of :class:`~scrapy.dupefilters.BaseDupeFilter`, this method
            may be omitted.
            """
            pass

class scrapy.dupefilters.BaseDupeFilter

  Dummy duplicate request filtering class (`DUPEFILTER_CLASS`) that does not filter out any request.

class scrapy.dupefilters.RFPDupeFilter(path: str | None = None, debug: bool = False, *, fingerprinter: RequestFingerprinterProtocol | None = None)

  Duplicate request filtering class (`DUPEFILTER_CLASS`) that filters out requests with the canonical (`w3lib.url.canonicalize_url()`) `url`, `method` and `body`.

  #### Job directory contents

  Warning

  The files that this class generates in the job directory are an implementation detail, and may change without a warning in a future version of Scrapy. Do not rely on the following information for anything other than debugging purposes.

  When using `JOBDIR`, seen fingerprints are tracked in a file named `requests.seen` in the job directory, which contains 1 request fingerprint per line.

### DUPEFILTER_DEBUG

Default: `False`

By default, `RFPDupeFilter` only logs the first duplicate request. Setting `DUPEFILTER_DEBUG` to `True` will make it log all duplicate requests.

### EDITOR

Default: `vi` (on Unix systems) or the IDLE editor (on Windows)

The editor to use for editing spiders with the `edit` command. Additionally, if the `EDITOR` environment variable is set, the `edit` command will prefer it over the default setting.

### EXTENSIONS

Default: `{}`

Component priority dictionary of enabled extensions. See Extensions.

### EXTENSIONS_BASE

Default:

    {
        "scrapy.extensions.corestats.CoreStats": 0,
        "scrapy.extensions.telnet.TelnetConsole": 0,
        "scrapy.extensions.memusage.MemoryUsage": 0,
        "scrapy.extensions.memdebug.MemoryDebugger": 0,
        "scrapy.extensions.closespider.CloseSpider": 0,
        "scrapy.extensions.feedexport.FeedExporter": 0,
        "scrapy.extensions.logstats.LogStats": 0,
        "scrapy.extensions.spiderstate.SpiderState": 0,
        "scrapy.extensions.throttle.AutoThrottle": 0,
    }

A dict containing the extensions available by default in Scrapy, and their orders. This setting contains all stable built-in extensions. Keep in mind that some of them need to be enabled through a setting.

For more information See the extensions user guide and the list of available extensions.

### FEED_TEMPDIR

The Feed Temp dir allows you to set a custom folder to save crawler temporary files before uploading with FTP feed storage and Amazon S3.

### FEED_STORAGE_GCS_ACL

The Access Control List (ACL) used when storing items to Google Cloud Storage. For more information on how to set this value, please refer to the column JSON API in Google Cloud documentation.

### FORCE_CRAWLER_PROCESS

Default: `False`

If `False`, Scrapy commands that need a CrawlerProcess will decide between using `scrapy.crawler.AsyncCrawlerProcess` and `scrapy.crawler.CrawlerProcess` based on the value of the `TWISTED_REACTOR` setting, but ignoring its value in per-spider settings.

If `True`, these commands will always use `CrawlerProcess`.

Set this to `True` if you want to set `TWISTED_REACTOR` to a non-default value in per-spider settings.

### FTP_PASSIVE_MODE

Default: `True`

Whether or not to use passive mode when initiating FTP transfers.

Note

Handling of this setting needs to be implemented inside the download handler, so it’s not guaranteed to be supported by all 3rd-party handlers.

### FTP_PASSWORD

Default: `"guest"`

The password to use for FTP connections when there is no `"ftp_password"` in `Request` meta.

Note

Paraphrasing RFC 1635, although it is common to use either the password “guest” or one’s e-mail address for anonymous FTP, some FTP servers explicitly ask for the user’s e-mail address and will not allow login with the “guest” password.

Note

Handling of this setting needs to be implemented inside the download handler, so it’s not guaranteed to be supported by all 3rd-party handlers.

### FTP_USER

Default: `"anonymous"`

The username to use for FTP connections when there is no `"ftp_user"` in `Request` meta.

Note

Handling of this setting needs to be implemented inside the download handler, so it’s not guaranteed to be supported by all 3rd-party handlers.

### GCS_PROJECT_ID

Default: `None`

The Project ID that will be used when storing data on Google Cloud Storage.

### ITEM_PIPELINES

Default: `{}`

A dict containing the item pipelines to use, and their orders. Order values are arbitrary, but it is customary to define them in the 0-1000 range. Lower orders process before higher orders.

Example:

    ITEM_PIPELINES = {
        "mybot.pipelines.validate.ValidateMyItem": 300,
        "mybot.pipelines.validate.StoreMyItem": 800,
    }

### ITEM_PIPELINES_BASE

Default: `{}`

A dict containing the pipelines enabled by default in Scrapy. You should never modify this setting in your project, modify `ITEM_PIPELINES` instead.

### JOBDIR

Default: `None`

A string indicating the directory for storing the state of a crawl when pausing and resuming crawls.

### LOG_ENABLED

Default: `True`

Whether to enable logging.

Note

This is a logging setting.

### LOG_ENCODING

Default: `'utf-8'`

The encoding to use for logging.

Note

This is a logging setting.

### LOG_FILE

Default: `None`

File name to use for logging output. If `None`, standard error will be used.

Note

This is a logging setting.

### LOG_FILE_APPEND

Default: `True`

If `False`, the log file specified with `LOG_FILE` will be overwritten (discarding the output from previous runs, if any).

Note

This is a logging setting.

### LOG_FORMAT

Default: `'%(asctime)s [%(name)s] %(levelname)s: %(message)s'`

String for formatting log messages. Refer to the Python logging documentation for the whole list of available placeholders.

Note

This is a logging setting.

### LOG_DATEFORMAT

Default: `'%Y-%m-%d %H:%M:%S'`

String for formatting date/time, expansion of the `%(asctime)s` placeholder in `LOG_FORMAT`. Refer to the Python datetime documentation for the whole list of available directives.

Note

This is a logging setting.

### LOG_FORMATTER

Default: `scrapy.logformatter.LogFormatter`

The class to use for formatting log messages for different actions.

### LOG_LEVEL

Default: `'DEBUG'`

Minimum level to log. Available levels are: CRITICAL, ERROR, WARNING, INFO, DEBUG. For more info see Logging.

Note

This is a logging setting.

### LOG_STDOUT

Default: `False`

If `True`, all standard output (and error) of your process will be redirected to the log. For example if you `print('hello')` it will appear in the Scrapy log.

Note

This is a logging setting.

### LOG_SHORT_NAMES

Default: `False`

If `True`, the logs will just contain the root path. If it is set to `False` then it displays the component responsible for the log output

Note

This is a logging setting.

### LOG_VERSIONS

Default: `["lxml", "libxml2", "cssselect", "parsel", "w3lib", "Twisted", "Python", "pyOpenSSL", "cryptography", "Platform"]`

Logs the installed versions of the specified items.

An item can be any installed Python package.

The following special items are also supported:

- `libxml2`

- `Platform` (`platform.platform()`)

- `Python`

### LOGSTATS_INTERVAL

Default: `60.0`

The interval (in seconds) between each logging printout of the stats by `LogStats`.

### MEMDEBUG_ENABLED

Default: `False`

Whether to enable memory debugging.

### MEMDEBUG_NOTIFY

Default: `[]`

When memory debugging is enabled a memory report will be sent to the specified addresses if this setting is not empty, otherwise the report will be written to the log.

Example:

    MEMDEBUG_NOTIFY = ['user@example.com']

### MEMUSAGE_ENABLED

Default: `True`

Scope: `scrapy.extensions.memusage.MemoryUsage`

Whether to enable the memory usage extension. This extension keeps track of a peak memory used by the process (it writes it to stats). It can also optionally shutdown the Scrapy process when it exceeds a memory limit (see `MEMUSAGE_LIMIT_MB`).

See Memory usage extension.

### MEMUSAGE_LIMIT_MB

Default: `0`

Scope: `scrapy.extensions.memusage.MemoryUsage`

The maximum amount of memory to allow (in megabytes) before shutting down Scrapy (if `MEMUSAGE_ENABLED` is `True`). If zero, no check will be performed.

See Memory usage extension.

### MEMUSAGE_CHECK_INTERVAL_SECONDS

Default: `60.0`

Scope: `scrapy.extensions.memusage.MemoryUsage`

The Memory usage extension checks the current memory usage, versus the limits set by `MEMUSAGE_LIMIT_MB` and `MEMUSAGE_WARNING_MB`, at fixed time intervals.

This sets the length of these intervals, in seconds.

See Memory usage extension.

### MEMUSAGE_WARNING_MB

Default: `0`

Scope: `scrapy.extensions.memusage.MemoryUsage`

The maximum amount of memory to allow (in megabytes) before sending a `memusage_warning_reached` signal (if `MEMUSAGE_ENABLED` is `True`). If zero, no signal will be sent.

See Memory usage extension.

### NEWSPIDER_MODULE

Default: `"<project name>.spiders"` (fallback: `""`)

Module where to create new spiders using the `genspider` command.

Example:

    NEWSPIDER_MODULE = 'mybot.spiders_dev'

### RANDOMIZE_DOWNLOAD_DELAY

Default: `True`

If enabled, Scrapy will wait a random amount of time (between 0.5 * `DOWNLOAD_DELAY` and 1.5 * `DOWNLOAD_DELAY`) while fetching requests from the same website.

This randomization decreases the chance of the crawler being detected (and subsequently blocked) by sites which analyze requests looking for statistically significant similarities in the time between their requests.

The randomization policy is the same used by wget `--random-wait` option.

If `DOWNLOAD_DELAY` is zero (default) this option has no effect.

### REACTOR_THREADPOOL_MAXSIZE

Default: `10`

The maximum limit for Twisted Reactor thread pool size. This is common multi-purpose thread pool used by various Scrapy components. Threaded DNS Resolver, BlockingFeedStorage, S3FilesStore just to name a few. Increase this value if you’re experiencing problems with insufficient blocking IO.

Note

This is a reactor setting.

### REDIRECT_PRIORITY_ADJUST

Default: `+2`

Scope: `scrapy.downloadermiddlewares.redirect.RedirectMiddleware`

Adjust redirect request priority relative to original request:

- a positive priority adjust (default) means higher priority.

- a negative priority adjust means lower priority.

### ROBOTSTXT_OBEY

Default: `True` (fallback: `False`)

If enabled, Scrapy will respect robots.txt policies. For more information see RobotsTxtMiddleware.

Note

While the default value is `False` for historical reasons, this option is enabled by default in settings.py file generated by `scrapy startproject` command.

### ROBOTSTXT_PARSER

Default: `'scrapy.robotstxt.ProtegoRobotParser'`

The parser backend to use for parsing `robots.txt` files. For more information see RobotsTxtMiddleware.

#### ROBOTSTXT_USER_AGENT

Default: `None`

The user agent string to use for matching in the robots.txt file. If `None`, the User-Agent header you are sending with the request or the `USER_AGENT` setting (in that order) will be used for determining the user agent to use in the robots.txt file.

### SCHEDULER

Default: `Scheduler`

The scheduler class to be used for crawling. See Scheduler for details.

### SCHEDULER_DEBUG

Default: `False`

Setting to `True` will log debug information about the requests scheduler. This currently logs (only once) if the requests cannot be serialized to disk. Stats counter (`scheduler/unserializable`) tracks the number of times this happens.

Example entry in logs:

    1956-01-31 00:00:00+0800 [scrapy.core.scheduler] ERROR: Unable to serialize request:
    <GET http://example.com> - reason: cannot serialize <Request at 0x9a7c7ec>
    (type Request)> - no more unserializable requests will be logged
    (see 'scheduler/unserializable' stats counter)

### SCHEDULER_DISK_QUEUE

Default: `'scrapy.squeues.PickleLifoDiskQueue'`

Type of disk queue that will be used by the scheduler. Other available types are `scrapy.squeues.PickleFifoDiskQueue`, `scrapy.squeues.MarshalFifoDiskQueue`, `scrapy.squeues.MarshalLifoDiskQueue`.

### SCHEDULER_MEMORY_QUEUE

Default: `'scrapy.squeues.LifoMemoryQueue'`

Type of in-memory queue used by the scheduler. Other available type is: `scrapy.squeues.FifoMemoryQueue`.

### SCHEDULER_PRIORITY_QUEUE

Default: `DownloaderAwarePriorityQueue`

Type of priority queue used by the scheduler.

Another available type is `ScrapyPriorityQueue`.

`DownloaderAwarePriorityQueue` works better than `ScrapyPriorityQueue` when you crawl many different domains in parallel.

### SCHEDULER_START_DISK_QUEUE

Default: `'scrapy.squeues.PickleFifoDiskQueue'`

Type of disk queue (see `JOBDIR`) that the scheduler uses for start requests.

For available choices, see `SCHEDULER_DISK_QUEUE`.

Use `None` or `""` to disable these separate queues entirely, and instead have start requests share the same queues as other requests.

Note

Disabling separate start request queues makes start request order unintuitive: start requests will be sent in order only until `CONCURRENT_REQUESTS` is reached, then remaining start requests will be sent in reverse order.

### SCHEDULER_START_MEMORY_QUEUE

Default: `'scrapy.squeues.FifoMemoryQueue'`

Type of in-memory queue that the scheduler uses for start requests.

For available choices, see `SCHEDULER_MEMORY_QUEUE`.

Use `None` or `""` to disable these separate queues entirely, and instead have start requests share the same queues as other requests.

Note

Disabling separate start request queues makes start request order unintuitive: start requests will be sent in order only until `CONCURRENT_REQUESTS` is reached, then remaining start requests will be sent in reverse order.

### SCRAPER_SLOT_MAX_ACTIVE_SIZE

Default: `5_000_000`

Soft limit (in bytes) for response data being processed.

While the sum of the sizes of all responses being processed is above this value, Scrapy does not process new requests.

### SPIDER_CONTRACTS

Default: `{}`

A dict containing the spider contracts enabled in your project, used for testing spiders. For more info see Spiders Contracts.

### SPIDER_CONTRACTS_BASE

Default:

    {
        "scrapy.contracts.default.UrlContract": 1,
        "scrapy.contracts.default.ReturnsContract": 2,
        "scrapy.contracts.default.ScrapesContract": 3,
    }

A dict containing the Scrapy contracts enabled by default in Scrapy. You should never modify this setting in your project, modify `SPIDER_CONTRACTS` instead. For more info see Spiders Contracts.

You can disable any of these contracts by assigning `None` to their class path in `SPIDER_CONTRACTS`. E.g., to disable the built-in `ScrapesContract`, place this in your `settings.py`:

    SPIDER_CONTRACTS = {
        "scrapy.contracts.default.ScrapesContract": None,
    }

### SPIDER_LOADER_CLASS

Default: `'scrapy.spiderloader.SpiderLoader'`

The class that will be used for loading spiders, which must implement the SpiderLoader API.

Note

This is a pre-crawler setting.

### SPIDER_LOADER_WARN_ONLY

Default: `False`

By default, when Scrapy tries to import spider classes from `SPIDER_MODULES`, it will fail loudly if there is any `ImportError` or `SyntaxError` exception. But you can choose to silence this exception and turn it into a simple warning by setting `SPIDER_LOADER_WARN_ONLY = True`.

Note

This is a pre-crawler setting.

### SPIDER_MIDDLEWARES

Default: `{}`

A dict containing the spider middlewares enabled in your project, and their orders. For more info see Activating a spider middleware.

### SPIDER_MIDDLEWARES_BASE

Default:

    {
        "scrapy.spidermiddlewares.httperror.HttpErrorMiddleware": 50,
        "scrapy.spidermiddlewares.referer.RefererMiddleware": 700,
        "scrapy.spidermiddlewares.urllength.UrlLengthMiddleware": 800,
        "scrapy.spidermiddlewares.depth.DepthMiddleware": 900,
    }

A dict containing the spider middlewares enabled by default in Scrapy, and their orders. Low orders are closer to the engine, high orders are closer to the spider. For more info see Activating a spider middleware.

### SPIDER_MODULES

Default: `["<project name>.spiders"]` (fallback: `[]`)

A list of modules where Scrapy will look for spiders.

Example:

    SPIDER_MODULES = ["mybot.spiders_prod", "mybot.spiders_dev"]

Note

This is a pre-crawler setting.

### STATS_CLASS

Default: `'scrapy.statscollectors.MemoryStatsCollector'`

The class to use for collecting stats, who must implement the Stats Collector API.

### STATS_DUMP

Default: `True`

Dump the Scrapy stats (to the Scrapy log) once the spider finishes.

For more info see: Stats Collection.

### TELNETCONSOLE_ENABLED

Default: `True` (`False` when `TWISTED_REACTOR_ENABLED` is `False`)

A boolean which specifies if the telnet console will be enabled (provided its extension is also enabled).

See also

Telnet console

### TEMPLATES_DIR

Default: `templates` dir inside scrapy module

The directory where to look for templates when creating new projects with `startproject` command and new spiders with `genspider` command.

The project name must not conflict with the name of custom files or directories in the `project` subdirectory.

### TWISTED_REACTOR_ENABLED

Default: `True`

Whether to install and use the Twisted reactor.

If this is set to `True`, Scrapy will use the Twisted reactor and will install one according to the `TWISTED_REACTOR` setting value when appropriate (e.g. when running via the command-line tool). This is the traditional mode of using Scrapy.

If this is set to `False`, Scrapy will use the asyncio event loop directly and will not attempt to install or use a reactor. Features that require a reactor won’t be available, but Twisted APIs that don’t require a reactor, including `Deferred` and `Failure`, will still be available. On the other hand, limitations related to Twisted reactors (such as not being able to start a reactor in the same process where a reactor was previously started and stopped) will not apply. This mode is currently experimental and may not be suitable for production use. It may also not be supported by 3rd-party code. See Using Scrapy without a Twisted reactor for more information about this mode.

Note

This is a pre-crawler setting.

Added in version 2.15.0.

### TWISTED_REACTOR

Default: `"twisted.internet.asyncioreactor.AsyncioSelectorReactor"`

Import path of a given `reactor`.

Scrapy will install this reactor if no other reactor is installed yet, such as when the `scrapy` CLI program is invoked or when using the `AsyncCrawlerProcess` class or the `CrawlerProcess` class.

If you are using the `AsyncCrawlerRunner` class or the `CrawlerRunner` class, you also need to install the correct reactor manually. You can do that using `install_reactor()`:

scrapy.utils.reactor.install_reactor(reactor_path: str, event_loop_path: str | None = None) → None

  Installs the `reactor` with the specified import path. Also installs the asyncio event loop with the specified import path if the asyncio reactor is enabled

If a reactor is already installed, `install_reactor()` has no effect.

`AsyncCrawlerRunner` and other similar classes raise an exception if the installed reactor does not match the `TWISTED_REACTOR` setting; therefore, having top-level `reactor` imports in project files and imported third-party libraries will make Scrapy raise an exception when it checks which reactor is installed.

In order to use the reactor installed by Scrapy:

    import scrapy
    from twisted.internet import reactor

    class QuotesSpider(scrapy.Spider):
        name = "quotes"

        def __init__(self, *args, **kwargs):
            self.timeout = int(kwargs.pop("timeout", "60"))
            super(QuotesSpider, self).__init__(*args, **kwargs)

        async def start(self):
            reactor.callLater(self.timeout, self.stop)

            urls = ["https://quotes.toscrape.com/page/1"]
            for url in urls:
                yield scrapy.Request(url=url, callback=self.parse)

        def parse(self, response):
            for quote in response.css("div.quote"):
                yield {"text": quote.css("span.text::text").get()}

        def stop(self):
            self.crawler.engine.close_spider(self, "timeout")

which raises an exception, becomes:

    import scrapy

    class QuotesSpider(scrapy.Spider):
        name = "quotes"

        def __init__(self, *args, **kwargs):
            self.timeout = int(kwargs.pop("timeout", "60"))
            super(QuotesSpider, self).__init__(*args, **kwargs)

        async def start(self):
            from twisted.internet import reactor

            reactor.callLater(self.timeout, self.stop)

            urls = ["https://quotes.toscrape.com/page/1"]
            for url in urls:
                yield scrapy.Request(url=url, callback=self.parse)

        def parse(self, response):
            for quote in response.css("div.quote"):
                yield {"text": quote.css("span.text::text").get()}

        def stop(self):
            self.crawler.engine.close_spider(self, "timeout")

If this setting is set `None`, Scrapy will use the existing reactor if one is already installed, or install the default reactor defined by Twisted for the current platform.

Changed in version 2.13: The default value was changed from `None` to `"twisted.internet.asyncioreactor.AsyncioSelectorReactor"`.

For additional information, see Choosing a Reactor and GUI Toolkit Integration.

Note

This is a reactor setting.

### URLLENGTH_LIMIT

Default: `2083`

Scope: `spidermiddlewares.urllength`

The maximum URL length to allow for crawled URLs.

This setting can act as a stopping condition in case of URLs of ever-increasing length, which may be caused for example by a programming error either in the target server or in your code. See also `REDIRECT_MAX_TIMES` and `DEPTH_LIMIT`.

Use `0` to allow URLs of any length.

The default value is copied from the Microsoft Internet Explorer maximum URL length, even though this setting exists for different reasons.

### USER_AGENT

Default: `"Scrapy/VERSION (+https://scrapy.org)"`

The default User-Agent to use when crawling, unless overridden. This user agent is also used by `RobotsTxtMiddleware` if `ROBOTSTXT_USER_AGENT` setting is `None` and there is no overriding User-Agent header specified for the request.

### WARN_ON_GENERATOR_RETURN_VALUE

Default: `True`

When enabled, Scrapy will warn if generator-based callback methods (like `parse`) contain return statements with non-`None` values. This helps detect potential mistakes in spider development.

Disable this setting to prevent syntax errors that may occur when dynamically modifying generator function source code during runtime, skip AST parsing of callback functions, or improve performance in auto-reloading development environments.

### Settings documented elsewhere:

The following settings are documented elsewhere, please check each specific case to see how to enable and use them.

- AUTOTHROTTLE_DEBUG

- AUTOTHROTTLE_ENABLED

- AUTOTHROTTLE_MAX_DELAY

- AUTOTHROTTLE_START_DELAY

- AUTOTHROTTLE_TARGET_CONCURRENCY

- CLOSESPIDER_ERRORCOUNT

- CLOSESPIDER_ITEMCOUNT

- CLOSESPIDER_PAGECOUNT

- CLOSESPIDER_PAGECOUNT_NO_ITEM

- CLOSESPIDER_TIMEOUT

- CLOSESPIDER_TIMEOUT_NO_ITEM

- COMMANDS_MODULE

- COMPRESSION_ENABLED

- COOKIES_DEBUG

- COOKIES_ENABLED

- FEEDS

- FEED_EXPORTERS

- FEED_EXPORTERS_BASE

- FEED_EXPORT_BATCH_ITEM_COUNT

- FEED_EXPORT_ENCODING

- FEED_EXPORT_FIELDS

- FEED_EXPORT_INDENT

- FEED_STORAGES

- FEED_STORAGES_BASE

- FEED_STORAGE_FTP_ACTIVE

- FEED_STORAGE_S3_ACL

- FEED_STORE_EMPTY

- FEED_URI_PARAMS

- FILES_EXPIRES

- FILES_RESULT_FIELD

- FILES_STORE

- FILES_STORE_GCS_ACL

- FILES_STORE_S3_ACL

- FILES_URLS_FIELD

- HTTPAUTH_DOMAIN

- HTTPAUTH_PASS

- HTTPAUTH_USER

- HTTPCACHE_ALWAYS_STORE

- HTTPCACHE_DBM_MODULE

- HTTPCACHE_DIR

- HTTPCACHE_ENABLED

- HTTPCACHE_EXPIRATION_SECS

- HTTPCACHE_GZIP

- HTTPCACHE_IGNORE_HTTP_CODES

- HTTPCACHE_IGNORE_MISSING

- HTTPCACHE_IGNORE_RESPONSE_CACHE_CONTROLS

- HTTPCACHE_IGNORE_SCHEMES

- HTTPCACHE_POLICY

- HTTPCACHE_STORAGE

- HTTPERROR_ALLOWED_CODES

- HTTPERROR_ALLOW_ALL

- HTTPPROXY_AUTH_ENCODING

- HTTPPROXY_ENABLED

- HTTPX_HTTP2_ENABLED

- IMAGES_EXPIRES

- IMAGES_MIN_HEIGHT

- IMAGES_MIN_WIDTH

- IMAGES_RESULT_FIELD

- IMAGES_STORE

- IMAGES_STORE_GCS_ACL

- IMAGES_STORE_S3_ACL

- IMAGES_THUMBS

- IMAGES_URLS_FIELD

- MEDIA_ALLOW_REDIRECTS

- METAREFRESH_ENABLED

- METAREFRESH_IGNORE_TAGS

- METAREFRESH_MAXDELAY

- PERIODIC_LOG_DELTA

- PERIODIC_LOG_STATS

- PERIODIC_LOG_TIMING_ENABLED

- REDIRECT_ENABLED

- REDIRECT_MAX_TIMES

- REFERER_ENABLED

- REFERRER_POLICIES

- REFERRER_POLICY

- REQUEST_FINGERPRINTER_CLASS

- RETRY_ENABLED

- RETRY_EXCEPTIONS

- RETRY_GIVE_UP_LOG_LEVEL

- RETRY_HTTP_CODES

- RETRY_PRIORITY_ADJUST

- RETRY_TIMES

- TELNETCONSOLE_HOST

- TELNETCONSOLE_PASSWORD

- TELNETCONSOLE_PORT

- TELNETCONSOLE_USERNAME