Download Firefox Developer Edition 121.0b4 (64-bit)

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

Updated: November 29, 2023

Size: 58 MB

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58 MB · November 29, 2023

Firefox%20Setup%20121.0b4.exe

Previous versions More »

136.0b9 February 23, 2025 68.1 MB 136.0b8 February 22, 2025 68.1 MB 136.0b7 February 19, 2025 68.1 MB 136.0b6 February 16, 2025 68.6 MB 136.0b5 February 14, 2025 68.5 MB 136.0b4 February 12, 2025 68.7 MB