Fern vs TypeSpec
Fern
buildwithfern.com
TypeSpec
typespec.ioSide by side
| Figure | Fern | TypeSpec |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | Yes | — |
| Web | Yes | Yes |
| Windows | Yes | Yes |
| macOS | Yes | Yes |
| Linux | Yes | Yes |
| API | Yes | — |
| Self-hosted | Yes | — |
| Plans published | 2 | 1 |
| Spec score · API Generation Software | 9.0 (#1) | 8.2 (#4) |
| Spec score · Code Generators | 9.0 (#2) | 8.2 (#12) |
| Integrations | Listed integrations include PostHog, Google Analytics, Segment, Mixpanel, FullStory, Intercom, Postman, and Context7. | The VS Code extension can import TypeSpec from existing OpenAPI 3 definitions and emit code from TypeSpec. |
Plans
In their own words
TypeSpec
TypeSpec is a language for defining API shapes and data models, then producing schemas, API specifications, code, and documentation. Its standard library supports OpenAPI 3.0, JSON Schema 2020-12, and Protobuf. OpenAPI output can feed tools for API gateways, code generation, and validation; JSON Schema output can be used to validate data built from shared models. The HTTP library’s `@useAuth` decorator lets authors attach documented security schemes—including HTTP authentication, API keys, OAuth2, and OpenID Connect—to services, interfaces, or operations. Editor support for Visual Studio Code and Visual Studio includes syntax help and completion; the VS Code extension adds diagnostics, formatting, quick fixes, refactoring, and documentation preview. Users can extend TypeSpec with emitters and decorators. The CLI is available through npm for Node.js or as an experimental standalone executable, and a browser playground is available. TypeSpec is open source and free: free. Its emitter framework is experimental, and client emitters for JavaScript, Python, Java, and C# are in preview.