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Yellow Lab Tools vs GTmetrix: catalog facts
Yellow Lab Tools	GTmetrix
Free Free and open source under the GPL-2.0 licence.	Freemium Free tests and a free account, with paid plans for more features.
Web, Self-hosted, Command line	Web
Checks front-end code quality as well as speed Detailed explanations of each issue	Test locations in 25 regions Configurable connection speed, user agent and cookies
Development has slowed, with the last repository push in early 2024 Docker image is maintained by a third party	Many options and locations require an account or paid plan
Downloadable app, Web application, Self-hosted	Web application, Hosted service
Open source	Closed source
License: GPL-2.0	License not stated
No account needed	Not stated if an account is needed
Not stated if it works offline	Needs internet
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 23, 2026

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