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Firefox Developer Edition vs Safari Technology Preview: catalog facts
Firefox Developer Edition	Safari Technology Preview
Free Free to download and use.	Free Free download from Apple.
Windows, macOS, Linux	macOS
Newest developer tools before they reach stable Firefox Builds for Windows, macOS and Linux, including ARM64	Latest WebKit engine ahead of stable Safari Runs side by side with regular Safari
Pre-release software, so it can be less stable than the regular release Not supported on Windows 8.1 and older or macOS 10.14 and older	macOS only Pre-release software that may be less stable
Downloadable app	Downloadable app
Open source	Closed source
License: MPL-2.0	License not stated
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 23, 2026	Official website Full listing and sources Checked September 24, 2026

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