Open-source WireMock Cloud alternatives

Karate is an open-source tool that unifies API testing, mocks, performance testing and UI automation in one framework with a single readable syntax. Tests are written as feature files, so people who are not Java developers can read and write them, and the project is written in Java.

Its documentation highlights the match keyword for validating complete responses, headers and arrays, parallel execution of features, scenarios and example rows, reusable flows by calling one feature from another, and test doubles that stand up HTTP, gRPC and message-queue mocks from a feature file. Karate v2 adds virtual threads, a single-binary CLI, JavaScript debugging and soft assertions. There are extensions for VS Code and IntelliJ, plus Karate Agent and Karate Xplorer products.

Tests can be run through JUnit, the command line or CI/CD pipelines. Karate is licensed under MIT, and topics mention BDD, Cucumber, contract testing, load testing and WebDriver. It suits QA engineers and developers who want one tool for API-level and UI-level checks.

Mockoon is an open-source tool for designing and running mock APIs. It combines a desktop application for building mock servers locally with a command-line tool for running those mocks in headless environments, and it requires no remote deployment or account.

API mocking reduces dependence on external services and their limits such as rate limits, costs and availability. Mockoon lets you control routes in detail, including HTTP methods and statuses, regex paths, file serving and custom headers. It supports OpenAPI import, JSON templating, HTTPS, a proxy forwarding mode and logs of incoming and forwarded requests. Teams can simulate errors and latencies and onboard new members with a consistent test environment.

The desktop app is built with Electron and TypeScript under the MIT licence and installs through Homebrew, winget, Chocolatey, the Windows Store, Snap or AUR. The CLI is also available as a Docker image for self-hosting mock APIs, and a separate cloud offering supports team collaboration, data sync and deployment of mock APIs.

Mocky is a simple application for generating custom HTTP responses, aimed at developers who need to test a web service client before the real backend exists, or who want to mock a specific response for a single test case. It lets a developer define a response and get a URL back that returns exactly that response when requested.

It is offered as a free and unlimited hosted service at mocky.io, with a FAQ describing allowed usage, though the maintainer does not guarantee the sustainability or stability of the service. The README notes that self-hosting a private instance was a work in progress at the time of writing, so self-hosting support may be limited or incomplete.

The backend API is written in Scala using the HTTP4s server, with mocks stored in a PostgreSQL database via Doobie, while the frontend is a TypeScript React and Redux application. Mocky is released under the Apache-2.0 license and is currently hosted on Clever Cloud.