As a developer, it can be incredibly frustrating and time-consuming to develop and test an application when you depend on a third-party API that is unfinished or unavailable. However, you can overcome this major pain point by using a mock REST API for testing.
API mocking is an extremely powerful concept that has become a crucial part of the modern software development and testing cycle. It allows you to test a wide range of potential scenarios and generates required use cases. This significantly contributes to future-proofing your application or software.
In this comprehensive guide, we will dive deep and explore some of the top tools to create mock REST APIs. But first, as a technology geek, let me share my perspective on what REST APIs are and how they can assist developers like you during development and testing.
What Is REST API? A Quick Primer for Developers
REST stands for REpresentational State Transfer. API is the acronym for Application Programming Interface. So in simple terms, a REST API refers to any web API that conforms to the architectural style of REST.
Also known as RESTful APIs, these are highly flexible and scalable. For this reason, this API type has become immensely popular for connecting applications and components in modern microservices architectures.
In my experience as a developer, here are some key benefits of using REST APIs:
They provide a standardized way for different systems to communicate with each other via HTTP requests. No need to write custom code for integration.
REST uses simple URIs to address resources. This provides a uniform interface for accessing data.
REST APIs are lightweight and fast. JSON is the most popular format for sending/receiving data.
They are easy to scale. You can distribute REST API requests across multiple servers.
REST is platform/language agnostic. You can build a REST API in any language like Java, Python, etc.
There is good documentation available for REST best practices. This makes it easy to design good APIs.
So in summary, REST APIs are simple, flexible, scalable and help developers like us build integrated systems rapidly. Now let‘s look at why mock APIs are so useful for testing.
Why Do Developers Need Mock APIs for Testing?
The lack of availability of an original API often causes frustrating testing roadblocks and delays in the development lifecycle.
Using a mock API means using a simulated REST API instead of the actual one. Although it does not contain all the functional/non-functional attributes of a real API, it does behave like one since it has the basic functionalities required for thorough testing.
Therefore, smart developers like us choose API mocks to provide support for incomplete test environments. Based on my experience, here are some key reasons why mock APIs are so useful:
Avoid external dependency: With a mock API, you don‘t have to wait for a third party to develop their API. This avoids delays.
Isolated testing: Mock APIs allow you to test in isolation without worrying about availability/errors in external services.
Simulate edge cases: You can simulate error conditions, edge cases, and unexpected responses easily.
Cost saving: Mock APIs save the cost of using paid external APIs, especially during early development stages.
Improved efficiency: Your team can work in parallel instead of waiting for an API to be ready.
Faster tests: Mock APIs tend to improve test execution times as no real network calls are made.
So in summary, using mock REST APIs can streamline and speed up testing for developers by providing a simulated environment. Next, let‘s look at some of the best tools available to easily create mock APIs.
Top 9 Tools to Create REST Mock APIs Quickly
I have compiled this list of the top tools and platforms that developers can use to create mock REST APIs for testing:
MockAPI is one of my personal favorites. It allows developers to create mock REST APIs through simple data modeling that involves quickly creating resources and their relationships.
It also supports one-click fake data generation with faker.js which is awesome! You don‘t have to build stubs manually.
Some standout features:
- Automatically generate fake data using faker.js library
- Create relationships between resources easily
- Customize responses using mock parameters
- Real-time updates when mocking rules are changed
- Share and clone projects for easy collaboration
I feel MockAPI is a great fit for developers who want to focus on mocking the endpoints and responses rather than building out realistic test data themselves. Recommended.
Beeceptor is another excellent tool I have used extensively for creating mock REST APIs with zero coding. As the name suggests, it lets developers create a mock API server rapidly with an intuitive UI.
Some cool features:
- Create endpoints with custom paths and HTTP methods
- Match requests with rules and return mock responses
- Monitor requests in real-time with the Request Inspector
- Share mock APIs easily as a URL
- Switch seamlessly between mock and real APIs
I like how easy it is to get started with Beeceptor. You can create endpoints in seconds and focus on mock responses rather than coding. Highly recommended for rapid prototyping.
3. API Mocha
API Mocha is a free platform that allows developers and testers to quickly create mock APIs for testing and prototyping purposes.
It allows you to create an unlimited number of API endpoints with custom responses in JSON/XML. You can get started instantly without needing to register.
Here are some useful features:
- Create unlimited API endpoints instantly
- Supports all HTTP methods like GET, POST, PUT etc
- Customize status codes and response body
- Import mocks from OpenAPI (Swagger) definitions
- Mocks can be shared easily using links
- Browser extension available for easy mocking
The free plan has a limit of 500 requests per day. But API Mocha is great for mocking a few quick endpoints without complexity.
Mockoon is a popular free and open-source tool for mocking REST and GraphQL APIs. I like that it can be used directly from a desktop app with no account required.
It allows developers to create an unlimited number of mocks with customizable routing logic. The mocks are hosted locally on your machine.
- Mock APIs without coding using the intuitive UI
- Route requests intelligently using regex match
- Testing integrated – export requests for integration testing
- Proxy existing APIs for mocking endpoints
- Import OpenAPI spec mocks in one click
Mockoon is very flexible with its dynamic response mocking capabilities. Highly recommended for developers.
Mocki provides a handy online tool for creating mock REST APIs without complexity. You can get started instantly without registration.
It allows you to create multi-endpoint APIs and view aggregated request logs in a simple dashboard.
Here are some useful capabilities:
- Add multiple endpoints with customizable paths
- CONFIG endpoint gives you endpoint documentation
- Supports all HTTP request methods
- Mock errors using custom status codes
- View request details like headers and params
- CLI available for local mocking without internet
The online tool is free to use with some basic limitations. Overall, Mocki is great for mocking a few quick endpoints during development.
Mockable provides a flexible API mocking solution that lets you create simulated REST and SOAP web service endpoints.
It offers a containerized approach – you can create a "Mockable Domain" and add team members to it for easy collaboration.
Some noteworthy features:
- Containerized domains for easy collaboration
- Custom endpoints with parameterized mocking
- View request history and response data
- Mock REST APIs and SOAP web services
- Integration with Postman for simplified collaboration
- Generous free tier with upgraded plans available
The parameterized mocking makes Mockable very flexible. It also has a generous free tier making it great for teams with limited mocking needs.
7. Castle Mock
Castle Mock is an open source mock server that lets you mock web services based on OpenAPI (Swagger), WADL, WSDL, and RAML definitions.
It can automatically mock any web service defined in those files making it stand out from inline mocking tools.
- Auto-mocking of web services defined in standard files
- Supports REST, SOAP, RPC, and GraphQL mocking
- Groovy scripts can be used for advanced response mocking
- Customize status codes, headers, and response body
- Run performance tests on mocks with JMeter
- CLI, Docker image and integrations available
Castle Mock is very flexible given its support for auto-mocking from standard files. Recommended for testing complex web service architectures.
QuickMocker is an interesting online REST API mocking tool created specifically for frontend developers and testers.
It makes it easy to mock REST endpoints without coding, directly from the browser.
Some useful features:
- Create mock REST endpoints instantly from the online editor
- Generates fake JSON data using faker.js library
- Import OpenAPI spec mocks with one click
- Restrict endpoint access for different user roles
- View request history and response data
- CLI available for local development usage
QuickMocker offers a very easy way for frontend developers to get mocked REST APIs up and running with zero coding. Worth checking out.
Intercept.rest provides developers and testers a novel way to mock REST APIs locally using a desktop app. This eliminates the need for an active internet connection.
It intercepts network calls made from the client and can map them to mocked responses without any code change needed.
- Map real API calls to mocks automatically
- View intercepted network requests easily
- Works locally without internet access
- Endpoint mock data can be imported from files
- Share mocks and requests with team members
- Available as Windows, Mac and Linux apps
Intercept.rest makes it incredibly simple to mock APIs directly used by your client apps. Recommended approach for integrated API mocking.
Key Considerations When Selecting a Mock API Tool
Based on my experience, here are some key aspects to evaluate when selecting a mock API tool:
Mocking capabilities – Evaluate supported protocols like REST, SOAP, GraphQL etc. Also check supported mocking styles – inline, parameterized, automated etc.
Ease of use – Look for an intuitive UI that makes API mocking rapid without coding.
Collaboration – Mocking tools that allow sharing mocks between team members enable easier testing collaboration.
Customization – For greater flexibility, look for dynamic mocking options, scripting support, custom headers etc.
Import options – Tools that support importing mocks and endpoints from OpenAPI, Postman etc accelerate development.
Monitoring – The ability to view request data can aid debugging during testing.
Scale – Some tools may limit the number of mocks while some support unlimited mocks on local/cloud.
Pricing – Look for free tiers and ensure upgrade pricing aligns with organizational needs.
Mock APIs have become an invaluable tool for testers and developers by enabling agile development independent of backend systems availability. They overcome testing bottlenecks and bring time/cost efficiencies.
In this guide, we explored the top 9 tools available to quickly mock REST APIs ranging from online tools like MockAPI and Mocki to local tools like Mockoon and Intercept.rest.
Each tool has its own strengths in terms of capabilities, ease of use and pricing. I recommend evaluating your specific mocking needs and constraints before picking the right tool for your projects.
I hope you enjoyed this guide and it helps you supercharge your development velocity using mock APIs. Feel free to reach out if you have any other questions!