MockServer

MockServer is ranked #3 of 27 in API mocking tools on Freedom251. It runs on API, Linux, macOS, Self-hosted, Web, Windows. There is a free plan.

MockServer plans and pricing

All plans

Free and open-source Free self-hosted · no SaaS account mock-server.com · 1 Oct 2026

Compared on API mocking tools

Free plan: Yes

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MockServer

Purpose: MockServer mocks and proxies HTTP, HTTPS and gRPC services for fast, isolated and deterministic testing.
Core roles: It can act as a mock, proxy and request-verification tool.
Protocol support: It supports HTTP/1.1, HTTP/2, HTTPS, SOCKS and experimental HTTP/3, with HTTP/3 using a separate UDP port.
API contracts: Mocks can be generated and traffic validated from OpenAPI or Swagger specifications.
Imports: Recorded traffic can be imported from browser HAR files and Postman collections.
Messaging and identity: It can mock gRPC services, AsyncAPI brokers including Kafka, MQTT and AMQP, and OAuth2/OIDC providers.
Chaos testing: It injects latency, error responses, dropped connections and malformed responses into mocked or proxied HTTP, gRPC and TCP traffic.
AI integration: Every instance includes an MCP server at /mockserver/mcp for assistants such as Claude Code, Cursor, Windsurf, Cline and OpenCode.
Deployment: It can run through Docker, an executable JAR, Helm/Kubernetes, Testcontainers, Homebrew or a JVM-less binary bundle.
Client integrations: Official clients are available for Java, JavaScript, Python, Ruby, Go, .NET, Rust and PHP, alongside the CLI and REST API.
Observability: A built-in web dashboard shows live logs, expectations and recorded traffic, while Prometheus metrics and OpenTelemetry tracing support shared environments.
Control-plane security: Control-plane requests can be authenticated with mutual TLS, JWT or both, and authorization can map OIDC scopes or groups to roles.
Security limitation: The /mockserver/status and /mockserver/ready health probes are always reachable without authentication or authorization.
Template safety: Velocity class loading is disabled by default and JavaScript templates cannot resolve Java classes unless explicitly allowed.
Price from: Free

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Where it ranks on Freedom251

Best API Mocking Tools in 2026#3 of 27
Best Integration Testing Tools in 2026#3 of 26
Best API Design Tools in 2026#4 of 26
Best Service Virtualization Software in 2026#3 of 20

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Sources

mock-server.com· checked 1 Oct 2026
mock-server.com/mock_server/getting_started.html· checked 1 Oct 2026
mock-server.com/mock_server/control_plane_authorisation· checked 1 Oct 2026
mock-server.com/mock_server/response_templates.html· checked 1 Oct 2026
mock-server.com/where/github.html· checked 1 Oct 2026