Hoverfly vs MockServer

Hoverfly Cloud is a hosted API simulation and mocking platform for testing without live API dependencies. It handles HTTP/S services including REST, SOAP, XML, JSON, and GraphQL. Users can capture and replay traffic, generate simulations from OpenAPI specifications, and match requests by methods, headers, parameters, and bodies. Simulations can delay responses, inject faults or errors, and modify replies. A command-line interface supports scripted configuration and testing pipelines. Hoverfly and hoverctl binaries run on macOS, Linux, and Windows, while documentation covers Docker and Kubernetes installation. The underlying Hoverfly framework is open source under Apache 2, has no GUI, and is generally run locally or in a user’s infrastructure. Cloud use cases include performance testing, functional testing, and development.

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.