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  • Overview
    • Introduction
    • How it works
    • Quickstart
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  • Working with SDKs
    • Project structure
    • Adding custom code
    • Migrating to Replay
    • Capabilities
  • Generators
  • Reference
    • generators.yml
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Working with SDKs

Capabilities

Fern SDKs are built to have every feature you need.
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Migrating to Replay

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Generating an SDK

Strongly typed

Move fast and break nothing with type safety

IDE support

Rich autocomplete and inline documentation in your editor

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Idiomatic method names

Fine-tune SDK resources and method names

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Schema validation

Fail fast if payloads diverge from your schema

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Discriminated unions

Fern SDKs include support for discriminated unions

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Multipart form data

SDKs that handle multipart form data

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Forward compatibility

SDKs that are fault-tolerant as your API evolves

Automated releases

Fern Autorelease automatically detects API changes, regenerates SDKs, and publishes to registries.

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Auto-pagination

Paginate through API responses easily with offset, cursor, and link-based pagination.

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OAuth token refresh

Fern supports OAuth as a first class citizen

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Retries with backoff

Automatically retry failed requests with exponential backoff

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Webhook signature verification

Verify the signature of incoming webhook requests

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Idempotency headers

Built-in protection against duplicate submissions

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Server-sent events

Stream JSON data from your server to your client (i.e. chat completions)

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Testing

Auto-generated and handwritten tests to ensure your SDK works in production

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Code snippets

No longer depend on manually written code snippets

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Augment with custom code

Extend the generated SDK to provide additional functionality

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Merging multiple APIs

Multiple API definitions. One SDK.

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WebSockets

Send and receive messages over WebSockets

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