kitten-diff(1)

Name
kitten-diff - Pretty, side-by-side diffing of files and images

A fast side-by-side diff tool with syntax highlighting and images

Major features

    •   Displays diffs side-by-side in the kitty terminal

    •   Does syntax highlighting of the displayed diffs, asynchronously, for maximum speed

    •   Displays images as well as text diffs, even over SSH

    •   Does recursive directory diffing
        Screenshot, showing a sample diff (images not supported)

Installation

Simply install kitty.

Usage

In the kitty terminal, run:

            kitten diff file1 file2

to see the diff between file1 and file2.

Create an alias in your shell's startup file to shorten the command, for example:

            alias d="kitten diff"

Now all you need to do to diff two files is:

            d file1 file2

You can also pass directories instead of files to see the recursive diff of the directory contents.

Keyboard controls
Action | Shortcut
Quit | Q, Esc
Scroll line up | K, Up
Scroll line down | J, Down
Scroll page up | PgUp
Scroll page down | PgDn
Scroll to top | Home
Scroll to bottom | End
Scroll to next page | Space, PgDn
Scroll to previous page | PgUp
Scroll to next change | N
Scroll to previous change | P
Increase lines of context | +
Decrease lines of context | -
All lines of context | A
Restore default context |
Search forwards | /
Search backwards | ?
Clear search | Esc
Scroll to next match | >, .
Scroll to previous match | <, ,
Copy selection to clipboard | y
Copy selection or exit | Ctrl+C

Integrating with git

Add the following to ~/.gitconfig:

            [diff]
                tool = kitty
                guitool = kitty.gui
            [difftool]
                prompt = false
                trustExitCode = true
            [difftool "kitty"]
                cmd = kitten diff $LOCAL $REMOTE
            [difftool "kitty.gui"]
                cmd = kitten diff $LOCAL $REMOTE

Now to use kitty-diff to view git diffs, you can simply do:

            git difftool --no-symlinks --dir-diff

Once again, creating an alias for this command is useful.

Why does this work only in kitty?

The diff kitten makes use of various features that are kitty only, such as the kitty graphics protocol, the extended keyboard protocol, etc. It also leverages terminal program infrastructure I created for all of kitty's other kittens to reduce the amount of code needed (the entire implementation is under 3000 lines of code).

And fundamentally, it's kitty only because I wrote it for myself, and I am highly unlikely to use any other terminals :)

Configuration

You can configure the colors used, keyboard shortcuts, the diff implementation, the default lines of context, etc. by creating a diff.conf file in your kitty config folder. See below for the supported configuration directives.

Diffing

    syntax_aliases

            syntax_aliases pyj:py pyi:py recipe:py

File extension aliases for syntax highlight. For example, to syntax highlight file.xyz as file.abc use a setting of xyz:abc. Multiple aliases must be separated by spaces.

    num_context_lines

            num_context_lines 3

The number of lines of context to show around each change.

    diff_cmd

            diff_cmd auto

The diff command to use. Must contain the placeholder _CONTEXT_ which will be replaced by the number of lines of context. A few special values are allowed: auto will automatically pick an available diff implementation. builtin will use the anchored diff algorithm from the Go standard library. git will use the git command to do the diffing. diff will use the diff command to do the diffing.

    replace_tab_by

            replace_tab_by \x20\x20\x20\x20

The string to replace tabs with. Default is to use four spaces.

    ignore_name

A glob pattern that is matched against only the filename of files and directories. Matching files and directories are ignored when scanning the filesystem to look for files to diff. Can be specified multiple times to use multiple patterns. For example:

            ignore_name .git
            ignore_name *~
            ignore_name *.pyc

Colors

    color_scheme

            color_scheme auto

Whether to use the light or dark colors. The default of auto means to follow the parent terminal color scheme. Note that the actual colors used for dark schemes are set by the dark_* settings below and the non-prefixed settings are used for light colors.

    pygments_style

            pygments_style default

The pygments color scheme to use for syntax highlighting. See pygments builtin styles for a list of schemes. Note that this does not change the colors used for diffing, only the colors used for syntax highlighting. To change the general colors use the settings below. This sets the colors used for light color schemes, use dark_pygments_style to change the colors for dark color schemes.

    dark_pygments_style

            dark_pygments_style github-dark

The pygments color scheme to use for syntax highlighting with dark colors. See pygments builtin styles for a list of schemes. Note that this does not change the colors used for diffing, only the colors used for syntax highlighting. To change the general colors use the settings below. This sets the colors used for dark color schemes, use pygments_style to change the colors for light color schemes.

    foreground, dark_foreground, background, dark_background

            foreground      black
            dark_foreground #f8f8f2
            background      white
            dark_background #212830

Basic colors

    title_fg, dark_title_fg, title_bg, dark_title_bg

            title_fg      black
            dark_title_fg white
            title_bg      white
            dark_title_bg #212830

Title colors

    margin_bg, dark_margin_bg, margin_fg, dark_margin_fg

            margin_bg      #fafbfc
            dark_margin_bg #212830
            margin_fg      #aaaaaa
            dark_margin_fg #aaaaaa

Margin colors

    removed_bg, dark_removed_bg, highlight_removed_bg, dark_highlight_removed_bg, removed_margin_bg, dark_removed_margin_bg

            removed_bg                #ffeef0
            dark_removed_bg           #352c33
            highlight_removed_bg      #fdb8c0
            dark_highlight_removed_bg #5c3539
            removed_margin_bg         #ffdce0
            dark_removed_margin_bg    #5c3539

Removed text backgrounds

    added_bg, dark_added_bg, highlight_added_bg, dark_highlight_added_bg, added_margin_bg, dark_added_margin_bg

            added_bg                #e6ffed
            dark_added_bg           #263834
            highlight_added_bg      #acf2bd
            dark_highlight_added_bg #31503d
            added_margin_bg         #cdffd8
            dark_added_margin_bg    #31503d

Added text backgrounds

    filler_bg, dark_filler_bg

            filler_bg      #fafbfc
            dark_filler_bg #262c36

Filler (empty) line background

    margin_filler_bg, dark_margin_filler_bg

            margin_filler_bg      none
            dark_margin_filler_bg none

Filler (empty) line background in margins, defaults to the filler background

    hunk_margin_bg, dark_hunk_margin_bg, hunk_bg, dark_hunk_bg

            hunk_margin_bg      #dbedff
            dark_hunk_margin_bg #0c2d6b
            hunk_bg             #f1f8ff
            dark_hunk_bg        #253142

Hunk header colors

    search_bg, dark_search_bg, search_fg, dark_search_fg, select_bg, dark_select_bg, select_fg, dark_select_fg

            search_bg      #444
            dark_search_bg #2c599c
            search_fg      white
            dark_search_fg white
            select_bg      #b4d5fe
            dark_select_bg #2c599c
            select_fg      black
            dark_select_fg white

Highlighting

Keyboard shortcuts

    Quit

            map q quit
            map esc quit

    Scroll down

            map j scroll_by 1
            map down scroll_by 1

    Scroll up

            map k scroll_by -1
            map up scroll_by -1

    Scroll to top

            map home scroll_to start

    Scroll to bottom

            map end scroll_to end

    Scroll to next page

            map page_down scroll_to next-page
            map space scroll_to next-page

    Scroll to previous page

            map page_up scroll_to prev-page

    Scroll to next change

            map n scroll_to next-change

    Scroll to previous change

            map p scroll_to prev-change

    Scroll to next file

            map shift+j scroll_to next-file

    Scroll to previous file

            map shift+k scroll_to prev-file

    Show all context

            map a change_context all

    Show default context

            map = change_context default

    Increase context

            map + change_context 5

    Decrease context

            map - change_context -5

    Search forward

            map / start_search regex forward

    Search backward

            map ? start_search regex backward

    Scroll to next search match

            map . scroll_to next-match
            map > scroll_to next-match

    Scroll to previous search match

            map , scroll_to prev-match
            map < scroll_to prev-match

    Search forward (no regex)

            map f start_search substring forward

    Search backward (no regex)

            map b start_search substring backward

    Copy selection to clipboard

            map y copy_to_clipboard

    Copy selection to clipboard or exit if no selection is present

            map ctrl+c copy_to_clipboard_or_exit

Source code for diff

The source code for this kitten is available on GitHub.

Command line interface

            kitten diff [options] file_or_directory_left file_or_directory_right

Show a side-by-side diff of the specified files/directories. You can also use ssh:hostname:remote-file-path to diff remote files.

  Options

    --context <CONTEXT>
        Number of lines of context to show between changes. Negative values use the number set in diff.conf. Default: -1

    --config <CONFIG>
        Specify a path to the configuration file(s) to use. All configuration files are merged onto the builtin diff.conf, overriding the builtin values. This option can be specified multiple times to read multiple configuration files in sequence, which are merged. Use the special value NONE to not load any config file.

        If this option is not specified, config files are searched for in the order: $XDG_CONFIG_HOME/kitty/diff.conf, ~/.config/kitty/diff.conf, $XDG_CONFIG_DIRS/kitty/diff.conf. The first one that exists is used as the config file.

        If the environment variable KITTY_CONFIG_DIRECTORY is specified, that directory is always used and the above searching does not happen.

        If /etc/xdg/kitty/diff.conf exists, it is merged before (i.e. with lower priority) than any user config files. It can be used to specify system-wide defaults for all users. You can use either - or /dev/stdin to read the config from STDIN.

    --override <OVERRIDE>, -o <OVERRIDE>
        Override individual configuration options, can be specified multiple times. Syntax: name=value. For example: -o background=gray

Sample diff.conf

You can download a sample diff.conf file with all default settings and comments describing each setting by clicking: sample diff.conf.

Author

Kovid Goyal

Copyright

2025, Kovid Goyal