Mockttp vs WireMock

Mockttp is a free, open-source JavaScript library for intercepting, transforming, or testing HTTP requests and responses. It supports integration tests in Node.js and browsers, including transparent proxying and HTTPS. Its tools can stub responses, verify requests, generate self-signed certificates for HTTPS mocking, and mock traffic inside or outside the process. It can also serve as the basis for custom proxies that capture, inspect, or rewrite traffic. For parallel tests, Mockttp can automatically configure ports, mock URLs, and proxy settings. It works with promise-capable testing tools and HTTP clients; Mocha, Chai, and Superagent appear in an example but are optional. Browser tests require an admin server running outside the browser. The setup guide warns against trusting a test certificate authority system-wide or sharing its private key, because either could allow an attacker to impersonate secure connections. Mockttp supports Linux, macOS, Windows, web, and self-hosted use.

WireMock simulates APIs and software dependencies so teams can test without live services, exercise edge cases, and build dependent features in parallel. It can match requests using URL patterns, headers, query parameters, cookies, and body content, then return templated responses or simulate delays, network faults, and malformed replies. It can also record interactions with real services and replay them during tests.

The project integrates with JUnit and other testing frameworks, with setup paths for Maven, Gradle, Scala SBT, standalone use, and Docker. Its documented capabilities cover HTTP-based protocols and REST, plus WebSockets, webhooks, HTTPS, gRPC, and GraphQL. WireMock Java is available as a standalone JAR, Docker image, experimental Helm chart, and NPM package; WireMock Cloud is another option. The Free plan costs nothing and includes 1,000 calls per month, one user, three mock APIs, and a 10 requests-per-second limit. Free and trial plans stop running mocks after their API quota is exceeded until the next quota cycle.