MockServer vs Servirtium

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.

Servirtium is an open-source testing library and command-line tool for recording HTTP interactions and replaying them offline. Saved interactions, called tapes, use readable Markdown that can include requests, responses, headers and bodies, making them shareable across languages and reviewable in Git diffs. A native record-and-replay engine has bindings for Go, Python, Java, .NET, Rust, Ruby, JavaScript and TypeScript, Dart, PHP, Haskell, Elixir, Pharo, Nim, Zig, Lua, Erlang and Gleam. It works with any unit-test or specification framework. The standalone CLI can serve tapes as HTTP stubs, lint them, and import or export HTTP Archive files, including captures from Chrome DevTools, Fiddler, Charles, mitmproxy and Postman. Redaction and tape normalization address transient values such as IDs and timestamps. Playback requires matching request headers and bodies unless masking is applied. Servirtium targets test automation, not production service replacement, and is available for API, Linux, macOS and self-hosted use.