Mockoon vs Mockttp

Mockoon is a free, open-source tool for designing and running mock APIs locally. It supports OpenAPI and can fit into existing applications and API design workflows. Mock behavior can use dynamic templating, rule matching, JSON databases, proxy mode, webhooks, and TLS. The tool can record requests and responses from a real API to create mocks, and it supports proxying and integration testing. The open-source version permits unlimited mock APIs and routes, including parallel runs. Its CLI can run mocks in headless automated environments such as CI, GitHub Actions, and Docker; mocks can also run in serverless environments including AWS Lambda and GCP/Firebase Functions. The desktop app stores mocks locally, works offline without an account, and reports that mock content and request data are not sent to Mockoon. Pro adds real-time team collaboration, synchronized mocks, and deployment management on private infrastructure; it can be self-hosted on-premises, in a private cloud, or on isolated or air-gapped networks. Team is listed at €10 a month, billed annually at €120/license/year, tax excluded. Eligible companies can request one 14-day self-hosted Pro trial with five license slots using a verified work email, without a payment method.

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.