Fern DefinitionIntegrations

Export from Fern Definition to OpenAPI

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Fern Definition isn’t recommended for new customers and Fern isn’t accepting feature requests for this format. It remains supported for existing users.

To prevent lock-in to the Fern Definition format, you can export your API definition to OpenAPI 3.1 at any time using the fern export command.

The path argument is the output file to write. Use a .yml or .json extension to choose the format of the generated spec.

terminal
$# Write the exported spec as YAML
$fern export path/to/openapi.yml
$
$# ...or as JSON
$fern export path/to/openapi.json

If you have multiple APIs defined in your fern/apis/ folder, use --api to specify which API to export.

terminal
$fern export --api public-api path/to/openapi.yml