Capabilities
These pages cover SDK generation configured with generators.yml. New projects use sdk-config.yml, so see the Current version of this page for up-to-date guidance. To move an existing project, follow the SDK Config migration guide, which walks through fern sdk migrate, and review the sdk-config.yml reference.
Rich autocomplete and inline documentation in your editor
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Fine-tune SDK resources and method names
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Fail fast if payloads diverge from your schema
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Fern SDKs include support for discriminated unions
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SDKs that handle multipart form data
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Fern Autorelease automatically detects API changes, regenerates SDKs, and publishes to registries.
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Paginate through API responses easily with offset, cursor, and link-based pagination.
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Fern supports OAuth as a first class citizen
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Automatically retry failed requests with exponential backoff
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Verify the signature of incoming webhook requests
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Built-in protection against duplicate submissions
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Stream JSON data from your server to your client (i.e. chat completions)
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Auto-generated and handwritten tests to ensure your SDK works in production
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No longer depend on manually written code snippets
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Extend the generated SDK to provide additional functionality
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Multiple API definitions. One SDK.
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Generate typed WebSocket clients with connection management and reconnection
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Typed XML serializers, parsers, and fluent builders for schemas with OpenAPI xml metadata
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