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Pesticide vs Web Developer: catalog facts
Pesticide	Web Developer
Free Free and open source under the MIT licence.	Free Free and open source under the GPL.
Browser extension	Browser extension
Makes layout overflow and nesting mistakes obvious instantly Available as a bookmarklet, so no extension is required	Dozens of page manipulations one click away, many still missing from devtools Same toolbar across Chrome, Firefox and Edge
Outlines change layout slightly on elements without a box-sizing reset Simple by design; developer tools do more	Much of its original value is now covered by built-in developer tools Interface is a dense menu-driven toolbar
Browser extension	Browser extension
Open source	Open source
License: MIT	License: GPL-3.0
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked September 22, 2026	Official website Full listing and sources Checked September 22, 2026

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