Copier vs TypeSpec

Copier has no write-up on Specifiction yet; its figures are above.

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.