Yaak

Yaak is a desktop API client for macOS, Windows and Linux that handles HTTP and REST, GraphQL, gRPC, WebSocket and server-sent events in one app. You organise requests into workspaces and folders, switch between environments, chain requests with template functions, and inspect responses and request timelines to see what an API is doing. Work stays on your machine: there is no account to create, the desktop app sends no telemetry, and collaboration happens through Git, with requests saved as YAML files that can live next to your code and secrets encrypted with a key held in the operating system keychain. Plugins, a command-line tool and an MCP server extend it to scripts and AI coding agents. Yaak is built by Gregory Schier, who created the Insomnia API client in 2014 and sold it in 2019; he launched Yaak publicly in January 2024 and left his job that May to work on it full-time through his company, Mountain Loop Labs. The source is MIT-licensed, the app is free for personal use, and a paid licence is needed for work use. It suits developers who want a fast, local-first alternative to cloud-centred API tools.