# Writing JSON Serialised Objects

Using JSON, we can serialise `cogent3` objects to a file for easy storage and retrieval.

## Create an example object to serialise

Let’s create a `LikelihoodFunction` object to use in this example. It is generated from fitting the General Nucleotide (GN) model to an alignment of BRCA1 in primates.

## `write_json` - writing JSON-serialised object to file

Using the `write_json` app, we can write out the likelihood function as a JSON-serialised object, making it easy to retrieve the model parameters for future reference if required.

We need to provide the `write_json` app with a data store to which it will write. Optionally when we apply the app we can specify an identifier for the data, which will name the file.

Note

Learn how to load a JSON serialised object in the loading JSON serialised objects section!

Tip

When running this code on your machine, remember to replace `path_to_dir` with an actual directory path.

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