head to head · open source
Ladybird vs Mercury
Ladybird has 66,807 GitHub stars, 3,194 forks, 535 open issues and last shipped yesterday. Mercury has 1,542 stars, 43 forks, 92 open issues and last shipped 3 months ago. Ladybird leads on adoption by 4,232% (66,807 vs 1,542 stars). Ladybird is written in C++ under BSD-2-Clause; Mercury is written in JavaScript under MPL-2.0. Ladybird has attracted 5% as many forks as stars, Mercury 3%. Ladybird was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (browser), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| Ladybird | Mercury | |
|---|---|---|
| GitHub stars | ★ 67K | ★ 1.5K |
| License | BSD-2-Clause | MPL-2.0 |
| Written in | C++ | JavaScript |
| Last push | 2026-11-02 | 2026-08-09 |
| Forks | ⑂ 3.2K | ⑂ 43 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Ladybird if
- You weight community size — 67K stars and counting
- You want the BSD-2-Clause license terms
- Your stack matches C++
- You value the larger contributor base for long-term maintenance
pick Mercury if
- You want the Mercury feature set and don't need the biggest community
- You prefer the MPL-2.0 license terms
- Your stack matches JavaScript
- You evaluated both and Mercury fits your workflow better
About Ladybird
Ladybird Ladybird is a truly independent web browser, using a novel engine based on web standards. [!IMPORTANT] Ladybird is in a pre alpha state, and only suitable for use by developers Features We aim to build a complete, usable browser for the modern web. Ladybird uses a multi process architecture with a main UI process, several WebContent renderer processes, an ImageDecoder process, and a RequestServer process. Image decoding and network connections are done out of process to be more robust against malicious content. Each tab has its own renderer process, which is sandboxed from the rest of the system. At the…
read the full Ladybird overview →
About Mercury
Mercury Browser Firefox fork with compiler optimizations and patches from Librewolf, Waterfox, Ghostery, and BetterFox. It aims to be the Firefox equivalent of my main project: Thorium (a Chromium fork). Patches See PATCHES.md Bugs See BUGS.md Building See BUILDING.md and DEBUGGING.md.
read the full Mercury overview →
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Frequently asked questions
Is Ladybird or Mercury more popular?
Ladybird has 66,807 GitHub stars and Mercury has 1,542. Ladybird has the larger community by that measure.
Are Ladybird and Mercury free?
Both are open source. Ladybird is licensed under BSD-2-Clause and Mercury under MPL-2.0. Neither carries a licence fee.
What is the difference between Ladybird and Mercury?
Ladybird is written in C++ and Mercury in JavaScript. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Ladybird or Mercury?
Choose Ladybird if you want the larger community (66,807 stars) or its BSD-2-Clause licence terms. Choose Mercury if its feature set, stack or MPL-2.0 licence fits better. Both are self-hostable.