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The Complete Guide to API Mocking: Essentials and Top Tools - February 2024 Review

Mock APIs can improve your software development by providing prototyping, testing and integration across multiple platforms. This article explains the benefits and top tools for API mocking.

Written byArman
Published OnWed Feb 09 2022
Last UpdatedTue May 07 2024

Mock APIs are important tools for accelerating the development process in microservices and Agile environments. They simulate external APIs; therefore, they enable development and testing and remove dependencies that might delay the project. This approach improves and accelerates workflow and lets teams keep their projects on schedule, which is important in today’s fast-paced development landscape.

What is API mocking?

API mocking simulates real API behaviour; therefore, application testing can be done without using real data. It can be used to ensure that applications work as they should and perform correctly under different conditions; how? Developers can create mock data and endpoints and use them to test various scenarios.

The Mock API can help you throughout your development process and increase your team’s development pace.

This strategy allows you to integrate and test features without depending on live APIs, thus speeding up the development process. Mock APIs mimic and simulate real APIs; they provide a realistic testing environment that can be hosted locally or on servers, and you can access it internally or publicly.

The Benefits of API Mocking

API mocking improves software development quality by speeding processes and improving results:

Accelerated Development Cycle

API mocking speeds up the feedback loop, which is critical when developing APIs with pending real data. It creates a realistic testing environment, allowing for faster problem detection, bug fixing, and system optimization. This approach accelerates development and assures that projects meet their schedules without additional delays.

Financial Efficiency

Mocking can lead to significant cost savings because it allows the development to continue regardless of whether the actual API is ready. It eliminates the need for third-party services during the early stages and expensive load-testing resources by simulating high system loads internally so you can save both time and money as it enables concurrent development and testing.

Enhanced Data Security

Using mock data reduces the security risks of leaking sensitive information in pre-release environments. It lets you test negative scenarios and potential vulnerabilities to ensure that security issues are solved before they become a threat in live systems.

Reliability and Precision

Using API mocking, you can specialize test scenarios to ensure your applications perform reliably under various conditions, including edge cases and errors. It’s pretty helpful in discovering performance bottlenecks and compatibility issues early on; therefore, your application performance will be more stable and reliable.

Seamless Cross-Platform Integration

API mocking allows you to easily test your applications across several platforms to ensure your applications interact seamlessly with different APIs. This is pretty useful for teams working on front-end and mobile integrations because it allows them to progress alongside back-end developments.

Continuous Collaboration and Integration

Using mock APIs removes development bottlenecks, allowing for uninterrupted workflows between front-end, mobile, and back-end teams. This collaborative approach allows for a dynamic development environment and ensures that API constructs are continuously evaluated against expected schemas and functionalities.

Immediate Feedback and Systematic Validation

In the environment created by Mock APIs, you can get immediate feedback and quickly identify integration issues. This collaboration among teams results in end-product quality improvement by ensuring that changes are done as soon as possible and that the final API meets the desired expectations.

API Mocking Examples

As you have learned, API mocking can improve project efficiency and quality. Let’s take a closer look at different scenarios where mock APIs were handy:

Rapid Prototyping

API mocking can be really helpful for startups and teams in speeding up the prototyping phase by allowing them to demonstrate product concepts without depending entirely on APIs. Rapid prototyping is critical for winning early-stage investments or partnerships.

Enhancing Automated Testing

You can enhance your automated testing process performance by using mock APIs because they provide a controlled environment for validating application responses and behaviours. By using them, you can ensure that applications remain robust and functional even if external APIs change.

Integrating a Third-Party API

API mocking simplifies the integration of third-party APIs because it simulates third-party endpoints, and developers can test and optimize the integration process early on.

Preparing for Feature Launches

Mock APIs allow teams to test new features in isolation and detect and fix any issues before public release. This approach is important to ensure new features and additions work as planned, resulting in a better user experience.

Running Performance Tests

Mock APIs are also useful for performance testing because they create a controlled environment where teams can test application efficiency and scalability. This testing improves application speed and ensures suitability for real-world use.

Top Tools for API Mocking

Here’s an overview of the top tools for API mocking:


Website: | Pricing: Free & Open-source, Paid plans from $10/month | Last Reviewed on: 2024-02-26

Mockoon, a free mock API tool

Mockoon is known for its open-source nature and ease of use in creating, configuring, and deploying mock APIs. Its simple user interface enables quick mock setup using templates appropriate for various environments, including serverless and automated testing setups. One important feature is its ability to serve mock APIs via TLS with a custom certificate, improving security during testing.


Website: | Pricing: Free, Paid plans start from $19 per user/month | Last Reviewed on: 2024-02-26

Postman mock API

Postman is an API Client application that provides us with many features, including API testing which we have covered in our Postman API testing article.

Postman is widely used in the developer community and provides complete functionality for creating and managing mock APIs and multiple testing customization options. Its ability to define mock server answers and collaborative features stands out, allowing teams to share workspaces and feedback loops. You can use this guide to configure and use a Postman mock server.


Website: | Pricing: Free, Paid plans start from $49/month | Last Reviewed on: 2024-02-26

Stoplight mock API

Stoplight lets you run your mock APIs and create your own JSON schema for responses.

Stoplight is built on the open-source application Prism. Using mocking, transformations, and validation, you can rapidly convert any Open API 2, Open API 3, or Postman Collection file into an API server. Stoplight enables you to construct fake Rest API endpoints with multiple http methods.

In the free edition of Stoplight, you may create mock APIs and produce documentation for them. The enterprise version allows you to use its version control system, Collaborative API Design, and create mock APIs for various projects without restrictions.

Stoplight has an intuitive design and good integration with most version control systems, including GitHub, GitLab, and Azure DevOps, making it even easier and more enjoyable.


Website: | Pricing: Free | Last Reviewed on: 2024-02-26

Mocky, a tool for building mock servers

Mocky is a cloud-based platform for rapid API mocking that requires minimal setup for instant mock creation. Its simple interface and lack of service limits or subscriptions make it a useful tool for developers looking for quick and effective mocking solutions.


Website: | Pricing: Free and Open-source | Last Reviewed on: 2024-02-26

Mountebank mock API

Mountebank, an open-source tool, excels in providing a platform for mock API development, supporting a variety of protocols such as HTTP, HTTPS, TCP, and SMTP. Its record and replay feature is very useful for capturing real API interactions and creating mocks, perfect for simulating real-world scenarios.


Website: | Pricing: Free and Open-source | Last Reviewed on: 2024-02-26

MockServer mock API

MockServer has rich request-matching features, allowing you to create mock APIs that can correctly respond to a variety of request types. Its ability to act as a proxy server, recording and creating mocks based on real API interactions, increases its usefulness in creating realistic testing environments.


Website: | Pricing: Free, Paid plan available | Last Reviewed on: 2024-02-26

WireMock mock API

WireMock is a simple tool for customizing responses and testing code, acting as an HTTP server for mock API configuration. Its support for request matching and response generation and a record and playback feature make it a comprehensive tool for detailed API mocking.


Website: | Pricing: Free, Paid plans start from $10/month | Last Reviewed on: 2024-02-26

Beeceptor, a powerful mock API tool

Beeceptor provides a simple, no-code platform for creating mock APIs, which is great for rapid prototyping and testing. It allows for easy inspection of HTTP requests, customizable mock responses, and CORS support.

Beeceptor’s unique proxy mode allows selective mocking and forwarding of API calls and simulates various network conditions. Notably, it supports A/B testing without requiring complex setup or redeployment, making it a versatile option for developers looking for efficient API mocking solutions.


Website: | Pricing: From $10/month | Last Reviewed on: 2024-02-26

Mocki, a mock API tool

Mocki offers a comprehensive solution for API mocking, starting with a free seven-day trial for new users.

It caters to developers looking for advanced capabilities such as GitHub integration, unlimited requests, improved support, and a monitoring dashboard, all for $10 per month.

To get started with Mocki, install an NPM package and create a configuration file for your project, supported by user-friendly documentation on its website.

Mocki is notable for its versatility in API creation and testing, with capabilities such as network delay simulation, customized response bodies, conditional responses, and random data generation. It allows developers to mimic various scenarios, including error circumstances and static responses, without relying on other services, hence speeding the development and testing process.


Website: | Pricing: Free, Paid plans are $5/month or $35/year | Last Reviewed on: 2024-02-26

MockAPI, a tool for creating mock APIs and severs

MockAPI is a minimalistic tool for quick API mockups, allowing users to generate custom data and handle RESTful operations easily.

It provides both free and paid programs, with the primary goal of prototyping, testing, and educating. The free version is limited, with only one project and four fake REST API endpoints. However, the paid plan considerably improves capabilities, allowing up to 20 projects and 50 fake REST API endpoints each.

MockAPI’s ability to generate fake data using faker.js improves the realism of mock APIs for testing scenarios. It also offers team collaboration, allowing users to add team members and work smoothly on API projects.

Comparison Table

ToolPricingUnique Features
MockoonFree & Open-source, Paid from $10/monthSimple UI, TLS support, serverless environments. CLI and cloud serverless compatible.
PostmanFree, Paid from $19/monthExtensive testing and collaboration features. Cloud-based platform with CLI for automation.
StoplightFree, Paid from $49/monthJSON schema for responses, integrates with CI/CD. Built on open-source Prism application.
MockyFreeMinimal setup, instant mock creation. Cloud-based platform for rapid API mocking.
MountebankFree and Open-sourceSupports multiple protocols, record and replay feature. Flexible tool for simulating services.
MockServerFree and Open-sourceRich request-matching, proxy server capabilities. Advanced request matching features.
WireMockFree, Paid availableHTTP server configuration, record and playback. Flexible API mocking with request matching.
BeeceptorFree, Paid from $10/monthProxy mode, simulates network conditions, supports A/B testing. Easy HTTP inspection and mocking.
MockiFrom $10/monthGitHub integration, network delay simulation. Advanced mocking capabilities with GitHub.
MockAPIFree, Paid $5/month or $35/yearQuick API mockups, generates custom data with faker.js. Simplifies RESTful operations.

Frequently Asked Questions

We got an answer for your questions

  • What is API mocking?

    API mocking is a technique that simulates actual API behaviour, allowing developers to test applications without relying on actual data. It enables the creation of mock data models and endpoints to ensure apps function correctly under diverse conditions.

  • How do Mock APIs improve software development?

    Mock APIs facilitate accelerated development cycles, financial efficiency, enhanced data security, reliability, precision, seamless cross-platform integration, and continuous collaboration. They enable immediate feedback and systematic validation, which is crucial for modern software engineering.

  • What are the benefits of API mocking?

    Benefits include faster feedback loops, cost savings by reducing dependency on live APIs, minimized security risks with mock data, improved application reliability, and the ability to test across different platforms and network conditions.

  • Can Mock APIs be used for automated testing?

    Yes, Mock APIs are integral to automated testing by providing a controlled environment to validate application responses and behaviours. They ensure applications remain robust and functional despite changes in external APIs.

  • What tools are available for API mocking?

    Top tools include Mockoon, Postman, Stoplight, Mocky, Mountebank, MockServer, WireMock, Beeceptor, Mocki, and MockAPI. Each tool offers unique features for different mocking needs, from rapid prototyping to detailed API simulation and testing.

  • What is the primary use case of mock APIs?

    Having a simulated version of your real APIs can help your team develop your project faster errors efficiently, and that is when mock APIs comes in handy.

  • Are there any Open-Source and free solutions for mock API?

    Yes, Mocky and Mockoon are both completely free and open-source that you can use in your project.

  • Can we simulate a slow internet connection using mock API tools?

    Yes, many of the available tools provide you with a feature to slow down your internet connection on purpose.

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