Insomnia is an open-source, cross-platform API client developed by Kong, designed for testing, debugging, and designing APIs across REST, GraphQL, gRPC, WebSockets, Server-Sent Events (SSE), and other HTTP-compatible protocols. It offers a lightweight, developer-friendly alternative to Postman with unlimited collection runs, native Git sync, AI-powered features, and full support for Model Context Protocol (MCP) servers. Insomnia streamlines API workflows through intuitive templating, powerful scripting (pre-request and after-response), environment management, and flexible storage options—local, cloud, or Git-based—making it essential for modern API development and collaborative testing. A key advantage is its simplicity and speed, which keeps developers focused on API functionality rather than wrestling with tooling complexity.