Download Firefox Developer Edition 139.0b1

Get the latest features, fast performance, and the development tools!

Updated: April 30, 2025

Size: 143 MB

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143 MB · April 30, 2025

Firefox%20139.0b1.dmg

Previous versions More »

139.0b5 May 09, 2025 143 MB 139.0b4 May 07, 2025 143 MB 139.0b3 May 04, 2025 143 MB 139.0b2 May 02, 2025 143 MB 139.0b1 April 30, 2025 143 MB 138.0b9 April 20, 2025 141 MB