Best Free Postman Alternatives for API Testing in 2025

Postman has become a popular choice for API development and testing, but it may not fit every developer’s needs.

This article helps you find the best Postman alternatives.

Key Features of Postman

Postman is a comprehensive API development platform that streamlines designing, testing, and managing APIs. Its robust feature set caters to developers, QA engineers, and teams working across various stages of the API lifecycle.

• Multiple Request Types: It supports multiple request types, including GET, POST, PUT, DELETE, and PATCH.
• Collections and Workspaces: Users can organize requests into collections and folders for better structure. Workspaces enable teams to share collections, environments, and resources to maintain project consistency.
• Automated Testing and Scripting: Postman supports automated testing using JavaScript. Tests can validate response status codes, headers, and body content.

• Mock Servers: Mock servers let developers simulate API endpoints before full implementation, allowing front-end work to proceed without waiting for back-end services.

• API Documentation Generation: Postman provides API documentation generation to help teams share and understand API endpoints clearly.
• Environment Variables: It supports environment variables to manage different setups (development, staging, production) without manually changing requests.
• Monitoring and Alerts: Postman offers detailed application monitoring capabilities to schedule automated runs of collections and alert teams of failures or issues.

• Integration with Development Tools: Postman integrates with popular tools and platforms such as GitHub, Jenkins, Slack, and many others for a smooth development workflow.
• GraphQL Support: The tool supports GraphQL APIs alongside REST APIs, allowing querying and testing with introspection and autocomplete.

Why Look for Postman Alternatives?

Postman is a powerful tool, but it may not meet every developer’s needs. Here are a few scenarios where developers consider alternatives:

• Resource Usage: Postman can consume significant system resources and feel sluggish when handling large projects or quick API testing, slowing down development workflows.
• Open Source Constraints: As a proprietary tool, Postman doesn’t offer the code transparency or modification flexibility that many developers value in open-source tools.
• Performance Testing Gaps: Postman mainly covers functional testing and doesn’t include built-in features for stress, load, or performance testing, limiting its scope for comprehensive API validation.
• Integration Challenges: While Postman offers some integrations, it may not fit seamlessly with complex CI/CD pipelines or developer ecosystems that rely on command-line or lightweight scripting tools.
• Browser-Based Flexibility: Postman’s focus on a desktop-first application can feel restrictive for developers who need quick, browser-based testing that fits better with their debugging and testing flows.

Top 10 Postman Alternatives

These alternatives address some of Postman’s limitations, such as resource usage, limited performance testing, and integration flexibility. We chose these tools based on their ability to fill these gaps and provide a better fit for different testing scenarios.

1. Requestly by BrowserStack

Requestly by BrowserStack is a streamlined tool tailored for quick API testing and debugging within the browser. It offers a developer-friendly experience that enables real-time monitoring and management of API calls, focusing on reducing setup overhead and boosting productivity. This makes it a practical choice for developers seeking efficiency and control without complex installations.

Key Features of Requestly:

• Redirect URL: Redirect requests to different URLs for testing or debugging without changing the source code.
• Replace Rule: Dynamically replace web strings to switch hosts, redirect API calls, change environments, and test new API versions without code changes.
• Override GraphQL APIs: Modify GraphQL queries and responses to test how applications interact with GraphQL endpoints.
• Modify HTTP Headers: Edit request and response headers to bypass CORS, remove X-Frame-Options, and manage Content-Security Policy settings.
• Modify API Response: Quickly modify and mock API responses to validate edge cases, simulate backend behavior, bypass backend complexities, and mock third-party APIs.
• Delay Request: Add artificial delays to simulate slow networks and test real-world user experience with advanced request matching.

Key Benefits of Requestly: 

Here are some reasons to use Requestly.

• Speeds up frontend development and testing by simulating API behavior before backend completion
• Enables early detection of bugs and edge cases through API response mocking
• Simplifies testing complex scenarios without altering backend code
• Supports testing across multiple devices by applying rules directly in the browser
• Helps teams work in parallel, reducing bottlenecks caused by backend delays

Requestly Pricing

Requestly has four pricing options, including a free version.

• Free: $0/month
• Lite (for individuals): $8/month
• Basic (for small teams): $15/month
• Professional (for enterprises): $23/month

2. Hoppscotch

Hoppscotch is an open-source API client that helps developers test APIs in a lightweight, responsive environment. It focuses on speed and simplicity for developers who want to explore and debug APIs quickly.

Key Features of Hoppscotch:

• Supports REST, GraphQL, WebSocket, and Server-Sent Events
• Save and organize requests in collections
• Environment variable management
• Shareable request links
• Open source and community-driven

3. HTTPie

HTTPie is a command-line HTTP client designed to simplify API interactions with straightforward syntax. It enables fast API calls and scripting in CLI environments, which is suitable for developers who prefer working from the terminal.

Key Features of HTTPie: 

• JSON output formatting
• Custom headers and authentication
• Support for file uploads and forms
• Plugin and scripting extensibility

4. RESTer

RESTer is a browser extension for Firefox and Chrome that provides basic HTTP request capabilities within the browser. It supports standard HTTP methods and allows saving requests for later use. Its lightweight design suits quick API checks without installing separate software.

Key Features of RESTer:

• Supports standard HTTP methods
• Custom headers and request bodies
• Format responses as JSON, XML, or HTML
• Import and export request collections

5. SOAPUI (Open Source)

SOAPUI is a widely used open-source tool for testing SOAP and REST APIs. It offers advanced capabilities like functional testing, security testing, and load testing. SOAPUI suits complex enterprise environments where detailed API validation is required.

Key Features of SOAPUI:

• Functional and regression testing
• Supports SOAP, REST, and JMS protocols
• Data-driven testing with external data sources
• Security testing features (e.g., SQL injection, XML threats)
• Load and performance testing

6. JMeter

Apache JMeter is an open-source load testing tool primarily designed to test performance on web applications and APIs. It simulates multiple users to evaluate server behavior under load. JMeter is popular for its extensibility and integration with CI/CD pipelines.

Key Features of JMeter:

• Load and stress testing for APIs and web services
• Supports HTTP, HTTPS, FTP, JDBC, and more
• Visualize test results with graphs and reports
• Distributed testing across multiple machines
• Plugin support for extended functionality

7. Karate Labs

Karate Labs is an open-source testing tool built for API and UI testing. It uses a syntax that’s easy to read and lets teams combine testing with performance checks and automation in one framework.

Key Features of Karate Labs:

• API test automation using simple scripts
• Built-in support for mocks and stubs
• Data-driven testing with JSON and CSV
• Performance testing capabilities
• Easy integration with CI/CD tools

8. Insomnia

Insomnia is a modern API client built to simplify the process of testing and debugging APIs. It’s designed to keep workflows consistent across teams, supporting multiple API protocols and a streamlined experience that helps developers focus on quality testing.

Key Features of Insomnia:

• Intuitive interface for sending HTTP requests
• Environment variable support
• Built-in code generation for API requests
• GraphQL and gRPC support
• Workspace and team collaboration features

9. Pyresttest

Pyresttest is a lightweight API testing tool that defines tests using configuration files. It’s ideal for developers who prefer a minimalist, script-based approach to API validation. Its flexibility makes it suitable for both simple checks and more complex scenarios.

Key Features of Pyresttest:

• Declarative tests with YAML/JSON
• Flexible response validation
• Supports authentication and dynamic variables
• CLI-friendly for easy automation
• Lightweight and script-driven approach

10. WireMock

WireMock is an open-source tool for mocking APIs and simulating web services. It helps teams test API integrations by mimicking real-world scenarios and enabling faster development.

Key Features of WireMock:

• Create dynamic mock APIs with configurable responses
• Simulate various API behaviors and latency
• Support for HTTPS and proxying
• Easy integration with testing frameworks
• Record and replay API interactions

Why Choose Requestly as Your Postman Alternative?

Requestly addresses the limitations of traditional API testing tools by focusing on essential features for fast and flexible testing. It’s lightweight and easy to use, offering precise control over HTTP requests and responses.

Requestly helps developers quickly modify requests and responses, mock APIs, and switch between different environments without rewriting code. It also integrates seamlessly into browser workflows for real-time testing.

Requestly also enables faster testing cycles by eliminating unnecessary tool switching and offers precise request matching to replicate real-world scenarios. Its built-in support for GraphQL, delay injection, and third-party API mocking ensures full control over testing workflows without leaving your browser.

In short, with Requestly, you can focus on creating reliable, scalable APIs that meet your project goals.

Talk to an Expert

Conclusion

Postman remains a powerful API testing tool, but it doesn’t always fit every developer’s workflow or project. Alternatives like Requestly, for instance, offer a flexible way to test APIs, tweak requests and responses, and even automate different API testing scenarios. It also helps developers and testers work more efficiently by allowing them to quickly modify API behavior in the browser without complex setups.

Try Requestly for Free