MockServer is an HTTP(S) mock server and proxy that supports multiple protocols, with dashboards, clients, and various deployment options. The repo is actively updated through 2026-08-04 and has a 4930 stars, 1113 forks.
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What it is
MockServer is an HTTP(S) mock server and proxy for testing. It supports mocking APIs, inspecting and modifying live traffic, and injecting failures. It speaks HTTP/1.1, HTTPS, HTTP/2, gRPC, WebSockets, raw TCP, and more, with experimental HTTP/3 and AI/LLM API support. It includes a built-in MCP server for AI coding assistants and a live dashboard to monitor requests and logs. It offers clients and integrations for Java, JavaScript/Node, Python and Ruby, plus JUnit and Spring support. It can run via Docker, Helm/Kubernetes, JAR or WAR, or as a JAR with a JVM-less bundle.
How it works
MockServer listens on a port and handles requests by matching them to configured expectations, returning defined responses. It can proxy and record traffic, modify requests/responses in flight, and apply chaos/injection rules to simulate failures. It supports dynamic responses through templates and callbacks, and can generate expectations from OpenAPI specifications. It also supports verification of received requests and can drive mocks from an OpenAPI spec or a recorded session.
Getting started
Getting started examples include starting MockServer with Docker, then creating an expectation and calling the mock:
# 1. Start MockServer
docker run -d --rm -p 1080:1080 mockserver/mockserver
# 2. Mock an endpoint: GET /hello -> 200 "Hello World"
# (MockServer exposes a REST control plane on the same port)
curl -X PUT http://localhost:1080/mockserver/expectation \
-H 'Content-Type: application/json' \
-d '{
"httpRequest": { "method": "GET", "path": "/hello" },
"httpResponse": { "statusCode": 200, "body": "Hello World" }
}'
# 3. Call your mock
curl http://localhost:1080/hello
# -> Hello World
Or install via Homebrew and run the mockserver command directly:
brew install mockserver
mockserver run --port 1080
Additional setup and usage guidance are available in the Docker documentation and the Self-Hosting MockServer guide.
Recent releases
Latest releases include 7.5.0 (2026-07-29) with breaking change: response templates can no longer reach arbitrary Java classes by default. Prior versions include 7.4.0 (2026-07-04) and 7.3.0 (2026-07-01).
Traction
Stars: 4930, Forks: 1113, Open issues: 12