Mercury
Thorium's Firefox-flavored sibling.
Firefox rebuilt with the same compiler-optimization treatment as Thorium, by the same developer. For Gecko fans chasing benchmark numbers.
- Engine
- Gecko
- License
- Open source
- Runs on
- Windows, Linux
- Top marks
- Raw speed, Extension ecosystem, Open source
- Updated
- September 2026
Why it shines
- Compiler-optimized Firefox builds
- Familiar Firefox experience
Worth knowing
- Same tiny-team, patch-lag caveat as Thorium
Origins
Mercury belongs to The Mozilla family — descended from Firefox.
Does well
Scorecard
- Tracking protection1/3
- Fingerprinting resistance0/3
- Anonymity0/3
- Built-in ad blocking0/3
- Customization2/3
- Keyboard control0/3
- Built-in tools0/3
- Minimal interface0/3
- Fresh design0/3
- Classic interface0/3
- Light on resources1/3
- Raw speed3/3
- Battery efficiency0/3
- Extension ecosystem3/3
- Cross-device sync0/3
- Site compatibility2/3
- Low maintenance0/3
- Open source3/3
- Independence2/3
- Built-in AI0/3
- Gaming features0/3
- Dev tooling0/3
0–3 on each of the 22 criteria the quiz and the guides rank by. How we score.
