High-integrity HTTP proxy for deterministic API record & replay. Works everywhere.

Local-first CLI for mocking HTTP APIs with YAML, JSON, and CSV-backed datasets

Try to make jwt authenticate, socket.io and other mock data

Apiary is an API design and documentation platform, now part of Oracle Cloud Infrastructure. With 486,000+ users and 591,000+ APIs managed, it uses API Blueprint and Swagger/OpenAPI specifications to produce interactive API documentation, mock servers, automated testing, and collaborative API design workflows.

Stoplight is a collaborative, design-first API platform providing a visual editor for OpenAPI specifications, interactive hosted documentation, automatic mock servers, API style guides and governance, and open-source tools including Prism (mock server), Spectral (JSON/YAML linter), and Elements (documentation components).

Sideko is an API tooling generation platform that uses OpenAPI Specifications to create SDKs, documentation sites, CLIs, and mock servers. The platform enables organizations to offer a complete suite of API developer tools without writing code, as Sideko generates the tooling automatically from OpenAPI specs.

Ambassador is a Kubernetes-native API Gateway built on Envoy Proxy, providing routing, load balancing, authentication, and observability for microservices.

Beeceptor is an API mocking, HTTP debugging, and proxy platform that lets developers create mock servers instantly without any coding. It supports REST, SOAP, GraphQL, and gRPC mocking, provides real-time HTTP traffic inspection, webhook testing, local tunneling, and AI-powered spec generation.

Mockoon is the easiest and quickest way to design and run mock REST APIs. Available as a free, open-source desktop application and CLI, it lets developers build, share, and serve realistic mock endpoints locally, in CI, or in containers. No remote deployment, no account required.

Postman is an API platform for building and using APIs. Postman simplifies each step of the API lifecycle and streamlines collaboration so you can create better APIs—faster.