Insomnia

Insomnia is an open-source, cross-platform API client for designing, debugging, and testing HTTP, GraphQL, gRPC, WebSockets, and Server-Sent Events (SSE) APIs. Originally created by Gregory Schier in 2014 as a streamlined alternative to Postman, it was acquired by Kong Inc. in 2019 and has grown to over 35,800 stars as of 2026. Unlike Postman, Insomnia is fully open-source under the MIT license with no forced account creation or cloud sync requirements for basic usage. Key features include: a clean desktop interface (available for macOS, Windows, and Linux via snap), request builder with template variables, environment management (dev, staging, production with secrets stored in GitIgnore files), GraphQL introspection and query builder with auto-completion, gRPC unary and streaming call support, WebSocket connection testing with message history, code generation in 20+ languages (cURL, Python requests, Go http, JavaScript fetch, Axios, Node.js, Java OkHttp, Rust reqwest), OpenAPI 3.0 and Swagger spec import/export, API mocking with mock servers, cookie jar management, SSL certificate handling, OAuth2 and API key authentication flows, and Git-based API design collaboration via Insomnia Design Documents. The Kong ecosystem integration enables syncing with Kong Gateway for declarative configuration. Available in three editions: Core (free), Designer (free with Git sync), and Enterprise (SSO, RBAC, audit logs).