Open source mock-server projects
Every project in the registry tagged mock-server, ranked by real GitHub adoption.
Test Automation Made Simple
Effortless API mocking for seamless development
A tool for mocking HTTP services
MockServer is an HTTP(S) mock server and proxy for testing that lets you mock APIs, inspect and modify live traffic, and inject failures. It supports HTTP/1.1,
Java client for Kubernetes & OpenShift
The open source, cloud native tool for API Mocking and Testing. Microcks is a Cloud Native Computing Foundation incubating project 🚀
Terminal API client for HTTP, GraphQL and gRPC. Plain .http files you can diff and version, with workflows, mocks, profiling, tracing, OpenAPI import, SSH tunne
WireMock.Net is a flexible product for stubbing and mocking web HTTP responses using advanced request matching and response templating. Based on WireMock Java,
Smocker is a simple and efficient HTTP mock server and proxy
Mock everything your AI app talks to — LLM APIs, MCP, A2A, AG-UI, vector DBs, search. One package, one port, zero dependencies.
Powerful friendly HTTP mock server & proxy library
Simulate API failures, throttling, and chaos — all from your command line.
Official master for the Greenmail project
HTTP mocking library for Rust
REST API Testing Tool for all levels in a Test Pyramid
mocker-api that creates mocks for REST APIs. It will be helpful when you try to test your application without the actual REST API server.
Related tags
Frequently asked questions
How many open source mock-server projects are there?
This registry tracks 16 projects tagged mock-server, with 45,889 GitHub stars between them. The most-adopted is karate at 9,002 stars.
Are these mock-server projects free to use?
Yes — 16 of the 16 carry an explicit open-source licence across 2 distinct licences, so there is no licence fee. Where a project also sells a hosted or enterprise version, the self-hosted path remains free.
Which mock-server project should I choose?
The list above is ranked by GitHub stars, but stars measure attention rather than fit. Check three things on each card: the licence (permissive versus copyleft), the language it is written in, and the last-push date — a high-star project that has not been pushed in a year is a liability.
Are these mock-server projects still maintained?
15 of the 16 were pushed in the last 90 days, and every card shows its exact last-push date so you can see the rest. Sort your shortlist by that date before committing to a migration.