MockServer vs Mockzilla

MockServer is a free, self-hosted tool for mocking and proxying HTTP, HTTPS, and gRPC services during isolated testing. It can verify requests as well as stand in for services. Teams can generate mocks and validate traffic against OpenAPI or Swagger contracts, or import recorded sessions from browser HAR files and Postman collections. Beyond HTTP services, it can mock gRPC, AsyncAPI brokers such as Kafka, MQTT, and AMQP, and OAuth2/OIDC providers. Its protocol coverage includes HTTP/1.1, HTTP/2, HTTPS, SOCKS, and experimental HTTP/3, which uses a separate UDP port. For fault-oriented testing, it can add latency, errors, dropped connections, and malformed responses to mocked or proxied traffic. Deployment options include Docker, an executable JAR, Helm/Kubernetes, Testcontainers, Homebrew, and a JVM-less bundle. A web dashboard displays logs, expectations, and recorded traffic; Prometheus metrics and OpenTelemetry tracing are available for shared environments. Each instance includes an MCP server at /mockserver/mcp. The /mockserver/status and /mockserver/ready probes remain reachable without authentication or authorization.

Mockzilla turns OpenAPI specifications or plain JSON files into hosted mock APIs for frontend work, integration tests, and demos. It generates responses from OpenAPI schemas and can validate requests against the specification. Users can inject latency or errors at service or endpoint level to exercise retry and fallback behavior. A proxy can forward requests to a real backend while supplying mock responses for routes that backend does not serve. Its GitHub Action creates a mock URL for each pull request, updates it on pushes, and cleans it up when the branch is gone. Mockzilla records request status and timing, and supports replaying individual requests or sets of requests. The CLI is MIT-licensed, works offline, and can run on a laptop or in CI; hosted cloud features are optional. The site also lists a GitHub Action and MCP server, with CLI setup instructions for Claude and Gemini. The Free plan is free, but API access is unavailable and request history lasts two hours. Hobby costs $10 a month. Uploaded content must not contain personally identifiable information, real financial data, health records, credentials, or other sensitive data.