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websocat vs Yaak: catalog facts
websocat	Yaak
Free Free and open source.	Freemium Yaak is MIT licensed and free to build and use. Development is funded by…
Command line	Windows, macOS, Linux
Quick interactive testing of WebSocket endpoints Works in pipes and shell scripts	Requests are stored as files on your machine, so a git repository is the shared collection REST, GraphQL, gRPC, WebSocket and Server-Sent Events in one client
Command line only Advanced options take time to learn	A much younger project than Postman, with a smaller community No hosted collaboration features if that is what you actually want
Downloadable app	Downloadable app
Open source	Open source
License not stated	License: MIT
No account needed	No account needed
Not stated if it works offline	Works offline
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 21, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.