The API Simulator is a Mendix module developed by Stoneworx that lets you generate responses for HTTP requests based on predefined templates. That makes it possible to test consumed APIs without any external dependencies.
Why use it
When developing Mendix applications that consume external APIs, testing can be challenging: external services may be unavailable during development, test environments may have rate limits or access restrictions, you need predictable responses for unit testing, and simulating error scenarios requires control over the response. The API Simulator solves this by letting you define mock responses that your application can use during development and testing.
Key features
- Template-based responses. Define response templates that match your expected API responses. The simulator returns them when your application makes HTTP requests.
- No external dependencies. Test your API integrations without access to the actual external service. Useful for offline development, or when external services are down.
- Flexible configuration. Configure different responses for different endpoints, HTTP methods and request patterns.
Requirements
- Mendix Studio Pro 10.24.3 or higher (module version 1.2.0, April 2026)
- Licence: Apache 2.0
Getting started
- Download the module from the Mendix Marketplace.
- Import it into your project.
- Configure your mock endpoints and responses.
- Use the simulator in your development and test environments.
The module comes with the full source code on GitHub, a demo sandbox and documentation. It is especially valuable for teams practising test-driven development or continuous integration, where reliable and predictable API responses are essential for automated testing.