Postman is the industry-standard API platform used by over 25 million developers worldwide. It provides a comprehensive suite of tools for designing, testing, documenting, and mocking APIs. The platform has evolved from a simple REST client to a full API development environment with collaboration features, automated testing, and CI/CD integration.
Starting priceFree/$14/mo
Strengths
Most comprehensive API platform available
Excellent collaboration and team features
Powerful automated testing with Newman CLI
Huge community and learning resources
Limitations
Can feel bloated for simple use cases
Desktop app resource intensive
Who it's for: Ideal for development teams of all sizes who need a complete API platform for design, testing, documentation, and collaboration.
Swagger and the OpenAPI Specification have become the industry standard for describing RESTful APIs. The ecosystem includes Swagger Editor for writing specs, Swagger UI for beautiful documentation, and Swagger Codegen for generating server stubs and client SDKs. The open-source nature means massive community support and integration with virtually every API tool.
Starting priceFree
Strengths
Industry-standard specification format
Massive ecosystem of tools
Code generation for 40+ languages
Free and open-source
Limitations
Requires learning YAML/JSON spec format
Fragmented tooling options
Who it's for: Best for teams adopting API-first design who want maximum flexibility and broad ecosystem compatibility.
Stoplight provides a visual-first approach to API design with a beautiful editor that makes working with OpenAPI specs accessible to non-technical stakeholders. The platform excels at governance with style guides that enforce consistency across APIs. Mock servers, documentation, and design reviews are built into a unified workflow.
Starting priceFree/$49/mo
Strengths
Best visual API design experience
Built-in style guides for governance
Automatic mock server generation
Beautiful hosted documentation
Limitations
Premium features require paid plans
Learning curve for full platform
Who it's for: Perfect for enterprises needing API governance, design consistency, and collaboration between technical and non-technical teams.
Insomnia offers a clean, focused API client that excels at REST and GraphQL testing. The interface is intuitive and fast, making it popular with developers who find Postman too heavy. Environment variables, plugins, and git sync provide power features without complexity. The open-source core version is completely free.
Starting priceFree/$5/mo
Strengths
Clean, lightweight interface
Excellent GraphQL support
Open-source core version
Fast and responsive
Limitations
Less comprehensive than Postman
Smaller community and ecosystem
Who it's for: Great for individual developers and small teams who want a fast, focused API client without the complexity of full platforms.
ReadMe specializes in creating beautiful, interactive API documentation that developers love. The platform generates API reference docs from OpenAPI specs with a "Try It" feature that lets developers test endpoints directly in the browser. Analytics show which endpoints are most used and where developers struggle.
Starting price$99/mo
Strengths
Beautiful, interactive documentation
Try-it-now API explorer
Analytics and usage insights
Easy to customize and brand
Limitations
Focused on docs, not full API lifecycle
Pricing can add up quickly
Who it's for: Ideal for API-first companies that prioritize developer experience and need analytics on how developers use their APIs.
Hoppscotch is a free, open-source API development ecosystem that runs entirely in the browser. It's incredibly fast and lightweight, supporting REST, GraphQL, WebSocket, and more. The platform is perfect for developers who want quick API testing without installing desktop apps or those who prefer open-source tools.
Starting priceFree
Strengths
Completely free and open-source
Web-based, no installation needed
Lightning-fast performance
Supports multiple protocols
Limitations
Limited team collaboration features
Fewer advanced features
Who it's for: Perfect for developers who want a fast, free, open-source API client that works in the browser without installation.
RapidAPI combines an API client with the world's largest API marketplace. Developers can discover, test, and connect to thousands of APIs from a single platform. For API providers, it offers a way to monetize and distribute APIs to millions of developers. The testing interface is solid for both consuming and building APIs.
Starting priceFree/$20/mo
Strengths
Largest API marketplace
Easy API discovery and testing
Monetization for API providers
Unified API management
Limitations
Focus on marketplace over dev tools
Can be overwhelming for simple projects
Who it's for: Best for developers consuming third-party APIs or API providers looking to distribute and monetize their APIs.
Our team tested each API development platform across real projects. Here's what we measured:
API Design (25%) — Visual design tools, OpenAPI support, and schema management.
Testing Capabilities (25%) — Request building, automation, and test scripting.
Documentation (20%) — Auto-generated docs, customization, and developer experience.
Collaboration (15%) — Team features, version control, and sharing.
Value for Money (15%) — Pricing relative to features for different team sizes.
How to Choose
Choose Postman if you need Complete API platform.
Choose Swagger/OpenAPI if you need API-first design.
Choose Stoplight if you need Enterprise governance.
Choose Insomnia if you need Lightweight testing.
Choose ReadMe if you need Developer documentation.
Common Questions
Postman is a comprehensive API platform with collaboration, documentation, and automation features. Insomnia is a lighter-weight API client focused on simplicity and speed. Choose Postman for teams, Insomnia for individual developers.
Swagger was the original name for the specification. It was donated to the Linux Foundation and renamed OpenAPI Specification. Swagger now refers to the tooling (Editor, UI, Codegen) while OpenAPI refers to the specification itself.
Hoppscotch is the best completely free option, being open-source and web-based. Postman and Insomnia also offer generous free tiers for individual developers.
Write an OpenAPI specification, then use tools like Swagger UI, ReadMe, or Stoplight to generate interactive documentation. Postman can also generate docs from collections.
