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TypeSpec
What it is
TypeSpec is a language for defining APIs and data models, then producing schemas, API specifications, code and documentation. Inspired by TypeScript, it provides a way to describe API shapes. Its standard library supports OpenAPI 3.0, JSON Schema 2020-12 and Protobuf. OpenAPI output can be used with tools for API gateways, code generation and data validation; JSON Schema output can validate data against shared models. TypeSpec offers editor support for Visual Studio Code and Visual Studio. The VS Code extension includes completion, formatting, diagnostics, quick fixes, refactoring and API documentation preview. Developers can create custom emitters or add metadata using decorators. The CLI is available through npm for Node.js or as a standalone executable marked experimental, and a browser playground is available. TypeSpec is an open-source, Microsoft-built, community-supported project listed as free. The emitter framework is experimental and under active development; documentation says only TypeScript is well supported for that framework at the time described. Client emitters for JavaScript, Python, Java and C# are in preview and subject to change.
For and against
For
- Open-source project listed as free
- Standard library supports OpenAPI, JSON Schema and Protobuf
- VS Code extension includes diagnostics and quick fixes
- Browser playground is available
- Supports custom emitters and decorators
Against
- Emitter framework is experimental
- Documentation says only TypeScript is well supported for the emitter framework
- Client emitters are in preview and subject to change
- VS Code extension collects usage data and sends it to Microsoft
The verdict
TypeSpec brings API modeling and generation into a language with editor support and a browser playground. Check the emitter and client-generation status if those outputs are central to your workflow.
Who it suits
TypeSpec suits developers defining API contracts and data models who want to generate specifications and schemas. It may be useful to teams working with OpenAPI, JSON Schema or Protobuf and supported editors.
Plans and prices
TypeSpec
Open-source project; TypeSpec CLI and online playground
Read 3 Oct 2026 · typespec.io
On the record
- Authentication modeling
- The HTTP library's @useAuth decorator supports applying authentication schemes to a service namespace, sub-namespace, interface, or operation.typespec.io · read 3 Oct 2026
- Browser playground
- The official site links to a TypeSpec Playground for trying TypeSpec in a browser.typespec.io · read 3 Oct 2026
- Built-in formats
- Its standard library supports OpenAPI 3.0, JSON Schema 2020-12, and Protocol Buffers (Protobuf).typespec.io · read 3 Oct 2026
- Client generation
- The client emitter guide lists JavaScript, Python, Java, and C# client emitters and says they are in preview and subject to change.typespec.io · read 3 Oct 2026
- Data validation
- The JSON Schema emitter can produce schemas from shared models for validating data.typespec.io · read 3 Oct 2026
- Editor integrations
- TypeSpec provides language support for VS Code and Visual Studio, including syntax highlighting and code completion.typespec.io · read 3 Oct 2026
- Editor support
- TypeSpec provides extensions for Visual Studio Code and Visual Studio.typespec.io · read 3 Oct 2026
- Emitter status
- The emitter framework is experimental and under active development, and the documentation says only TypeScript is well supported at the time of that page.typespec.io · read 3 Oct 2026
- Extensibility
- Developers can write custom emitters or add metadata with custom decorators.typespec.io · read 3 Oct 2026
- Installation
- The CLI is available as an npm package for Node.js or as a standalone executable marked experimental; installation instructions cover macOS, Windows, and Linux.typespec.io · read 3 Oct 2026
- Integrations
- The VS Code extension can import TypeSpec from existing OpenAPI 3 definitions and emit code from TypeSpec.typespec.io · read 3 Oct 2026
- Language
- TypeSpec is inspired by TypeScript and is described as a lightweight language for defining API shapes.typespec.io · read 3 Oct 2026
- Maker
- TypeSpec describes itself as a Microsoft-built, community-supported project.typespec.io · read 3 Oct 2026
- Online access
- The site provides an online playground for trying TypeSpec.typespec.io · read 3 Oct 2026
- OpenAPI workflow
- TypeSpec can generate OpenAPI specifications for use with tools for API gateways, code generation, and data validation.typespec.io · read 3 Oct 2026
- Output formats
- The standard library supports OpenAPI 3.0, JSON Schema 2020-12, and Protobuf.typespec.io · read 3 Oct 2026
- Pricing
- The official homepage and documentation pages reviewed present TypeSpec as an installable project and do not list paid plans or prices.typespec.io · read 3 Oct 2026
- Publisher and support
- TypeSpec is described as a Microsoft-built, community-supported project.typespec.io · read 3 Oct 2026
