Imposter: Scriptable, multipurpose mock server

Mock server for REST APIs, OpenAPI (and Swagger) specifications, SOAP web services (and WSDL files), Salesforce and HBase APIs.

• Run standalone mock servers in Docker, Kubernetes, AWS Lambda or on the JVM.
• Embed mocks within your tests (JVM or Node.js) to remove external dependencies.
• Script dynamic responses using JavaScript, Groovy or Java.
• Capture data from requests, then store it or return a templated response.
• Proxy an existing endpoint to replay its responses as a mock.

Read the documentation here

Features

• run standalone mocks in place of real systems
• turn an OpenAPI/Swagger file or WSDL file into a mock API for dev or QA (use it before the real API is built)
• decouple your integration tests from the cloud/back-end systems and take control of your dependencies
• validate your API requests against an OpenAPI specification
• capture data to retrieve later, or use in templates to for conditional responses
• proxy an existing endpoint to replay its responses as a mock

Send dynamic responses:

• Provide mock responses using static files or customise behaviour based on characteristics of the request.
• Power users can control mock responses with JavaScript or Java/Groovy script engines.
• Advanced users can write their own plugins in a JVM language of their choice.

Getting started

The quickest way to get up and running is to use the free cloud-hosted service at mocks.cloud

User documentation

Read the user documentation here

Tutorials

• Mocking APIs with OpenAPI and Imposter
• Mocking REST APIs with Imposter
• Mocking SOAP web services with Imposter

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Mock types

Imposter provides specialised mocks for the following scenarios:

• OpenAPI - Support for OpenAPI (and Swagger) API specifications.
• REST - Mocks RESTful or plain HTTP APIs.
• SOAP - Support for SOAP web services (and WSDL files).
• HBase - Basic HBase mock implementation.
• SFDC (Salesforce) - Basic Salesforce mock implementation.
• WireMock - Support for WireMock mappings files.

These use a plugin system, so you can also create your own plugins, using any JVM language.

Example

$ imposter up

Starting server on port 8080...
Parsing configuration file: someapi-config.yaml
...
Mock server is up and running

Your mock server is now running! Here Imposter provides HTTP responses to simulate an API that accepts users and returns a dynamic response containing the user ID from the request.

$ curl -v -X PUT http://localhost:8080/users/alice

HTTP/1.1 201 Created
Content-Type: application/json

{ "userName": "alice" }

This is a trivial example, which you can extend with conditional logic, request validation, data capture and much more...

How to run Imposter

There are many ways to run Imposter.

Standalone mock server

• Using the command line client - see Imposter CLI
• As a Docker container - see Imposter Docker container
• As a Lambda function in AWS - see Imposter AWS Lambda
• As a JAR file on the JVM - see Imposter JAR file

Embedded in tests

• Embedded within your Java/Kotlin/Scala/JVM unit tests - see JVM bindings
• Embedded within your JavaScript/Node.js unit tests - see JavaScript bindings

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Recent changes and Roadmap

For recent changes see the Changelog, or view the Roadmap.

Contributing

• Pull requests are welcome.
• PRs should target the develop branch.

Author

Pete Cornish (outofcoffee@gmail.com)