Open source
Joi
Schema description and validation library for JavaScript objects
Design and SDKsSchema validation for JS
Alternatives to JSON Schema
12 tools like JSON Schema, chosen by what they do. About JSON Schema
Open source
TypeSpec
Code-first language to define APIs and emit OpenAPI or JSON Schema
Design and SDKsDesign APIs with code
Open source
OpenAPI Generator
Generates API clients, server stubs and docs from OpenAPI
Design and SDKsGenerate clients from OpenAPI
Freemium
Fern
Generate SDKs, API docs and a CLI from an OpenAPI spec
Design and SDKsSDKs and docs from your API
Freemium
Apiary
Hosted platform to design, prototype, document and test APIs
Design and SDKsAPI design and docs platform
Open source
Scalar
Hosted API docs, typed SDKs and MCP servers from an OpenAPI file
Design and SDKsModern OpenAPI docs and client
Open source
AsyncAPI
Open source specification and tools for event-driven APIs
Design and SDKsSpec for event driven APIs
Curated
Bump.sh
Hosted API docs and MCP servers, built from your OpenAPI spec
Design and SDKsAPI docs with changelogs
Open source
Zod
TypeScript-first schema validation with static type inference
API DesignTypeScript schema validation
Open source
Open source
REST Assured
Java library for testing and validating REST APIs with simple syntax
Mocking TestingJava REST API testing
Open source
OpenAPI
Open standard for describing HTTP APIs in a machine-readable way
API DesignThe OpenAPI standard