APIs

API development platform for building, testing, and managing APIs

Query language and runtime for APIs

API documentation and design tools

Cross-platform REST client and API design tool

Comprehensive GraphQL platform for building connected applications

Java library for testing REST services with behavior-driven development

Apache APISIX is a dynamic, high-performance, open-source API gateway and AI gateway. Features include load balancing, authentication, rate limiting, AI proxying, LLM load balancing, and 100+ plugins.

REAL API Design-first Development Platform. Design. Debug. Test. Document. Mock. Build APIs Faster & Together.

Open source tools to easily build and maintain your event-driven architecture. All powered by the AsyncAPI specification, the industry standard for defining asynchronous APIs.

Create AI-powered mock servers in seconds. Generate realistic responses from prompts or real traffic for REST, SOAP, GraphQL, and gRPC. No code, no dependencies. Free

Bruno is the Git-native API client for REST, GraphQL, gRPC and Websocket. A local and open-source solution to Postman. Fast, developer-first, and no cloud syncing.

Buf is the toolchain for Protobuf, gRPC, and ConnectRPC - lint and generate code with the Buf CLI, publish and govern schemas on the Buf Schema Registry.

One platform to ship the docs your developers love and the MCP servers your agents can actually rely on. From OpenAPI to production, with built-in governance, authentication and observability.

Start with OpenAPI. Generate SDKs in multiple languages, interactive API documentation, and an agent-first CLI.

Gravitee is the AI Agent Management platform, securing, observing, and governing every AI agent, API, and event interaction at enterprise scale.

A high-performance, open source universal RPC framework

Hasura delivers accurate, fast, and secure data access for AI and digital experiences. Trusted by data leaders and developers at Fortune 100 companies and high-growth AI and digital natives.

Helps you create requests faster, saving precious time on development.

Making APIs simple and intuitive for those building the tools of our time.

Hurl, run and test HTTP requests with plain text and curl. Hurl can run fast automated integration tests.

k6 is an open-source tool and cloud service that makes load testing easy for developers and QA engineers.

From APIs to AI, Kong is the fabric of modern connectivity. Centralize LLM access, automate API workflows, and secure your digital ecosystem at scale.

KrakenD is a stateless, high-performance API gateway built for modern microservices. Open source, self-hosted, and trusted by enterprises worldwide.

Microcks is Open Source cloud-native tool for API Mocking and Testing

Mockoon is the easiest and quickest way to run mock REST API servers. No remote deployment, no account required, free, open source and cross-platform.

Fast, easy and reliable testing for integrating web apps, APIs and microservices

Extensible high-performance GraphQL APIs backed primarily by PostgreSQL

ReadMe helps you create beautiful, interactive API documentation that developers love.

OpenAPI-generated documentation tool with 24k+ stars on Github - make APIs your company's superpower.

Create beautiful docs, SDKs and secure MCP servers from your API. Scalar keeps every interface in sync as your API evolves.

Open-source tool for generating API tests from OpenAPI and GraphQL schemas using property-based testing.

The AI control plane for discovering, securing, and governing AI agents, MCP servers, and AI applications across your enterprise.

Svix is the enterprise-ready webhook platform delivering billions of webhooks every month for fast-growth startups and Fortune 500 companies including Brex, Benchling, and Drata. Send and receive webhooks at scale with retries, signature verification, and a managed dashboard.

End-to-end typesafe APIs made easy. Automatic typesafety & autocompletion inferred from your API-paths, their input data, & outputs 🧙‍♂️

Our API Management platform is fast, scalable, modern. Including an open source API Gateway, Analytics, Dev Portal and Dashboard

WireMock is a tool for building mock APIs. API mocking enables you build stable, predictable development environments when the APIs you depend on are unreliable or don’t exist.

Build and run your supergraph with governance and no lock-in. WunderGraph Cosmo is the open-source, enterprise-ready platform for teams scaling from the first subgraph to thousands of daily operations.

Secure, govern, and observe every API, LLM, and MCP call on one programmable policy engine. AI Gateway, MCP Gateway, MCP Server, and API management — fully managed, live in minutes.