Get easy mocking of systems via HTTP/HTTPS with MockServer, ideal for startup founders integrating with multiple services, backed by 4.9k+ GitHub stars
intermediateโฑ 30 minutes๐ต Free
4,922 stars1,112 forksJavaQuality 8/10Updated 7/23/2026100% free ยท open source
What it is
Create a mock version of any system you integrate with via HTTP or HTTPS to test it without using the real thing, like a mock Amazon server to test your e-commerce app.
What you can make with it
Automations that simulate real-world interactions with your app or service, like a mock Stripe customer to test your payment processing.
How it helps
Allows you to test and validate your app's behavior without actually making requests to external services, reducing potential errors and data breaches.
Real use case example
"A founder wants to test the payment processing of their new e-commerce app. They set up a mock Stripe server using MockServer and create a few test customers. They then write a script to simulate real payments and test the app's behavior. After testing, they know their app will work seamlessly with Stripe."
If you're new
Pick this up if you're new to testing and mocking APIs, especially if you're building an e-commerce or finance app that interacts with external services.
If you're senior
A senior engineer or architect who needs to test and validate complex system interactions with multiple external services would reach for this skill.
Common confusion cleared up
The most common confusion is thinking MockServer is only for testing external APIs, when in fact it can also be used to mock internal services or APIs for debugging purposes.
Best inside these AI tools
Any AI ClientCursor
Pairs with
any external APIStripe webhookNotion database
Why we list it on WorkflowStacks: This skill is included in the marketplace as it's a free and open-source tool for mocking and testing external APIs in a development environment.
What it does
MockServer enables easy mocking of any system you integrate with via HTTP or HTTPS, allowing for testing and development without relying on actual external services
โขWhen integrating with multiple external services and need to test how your application behaves with different responses
โขWhen developing against an API that is still in development or has rate limiting
โขWhen testing error scenarios or edge cases that are difficult to replicate with real services
Quick start
1Run MockServer by executing the command `mvn test -Dmockserver.mock.port=1080` in the cloned repository
2Configure MockServer to expect a request by creating a JSON expectation file, for example `src/main/java/org/mockserver/examples/mockserver/expectation.json`
3Use the MockServer Java client to send a request to the mock server by adding the dependency to your `pom.xml` file and using the `MockServerClient` class
4Verify the mock server received the expected request by checking the logs or using the MockServer REST API
5Reset the mock server state by sending a `RESET` request to the MockServer REST API