head to head · open source
Zen Browser vs extism
Zen Browser has 44,486 GitHub stars, 1,755 forks, 689 open issues and last shipped yesterday. extism has 5,764 stars, 168 forks, 54 open issues and last shipped 16 days ago. Zen Browser leads on adoption by 672% (44,486 vs 5,764 stars). Zen Browser is written in C++ under MPL-2.0; extism is written in Rust under BSD-3-Clause. Zen Browser has attracted 4% as many forks as stars, extism 3%. Zen Browser was the more recently maintained of the two, and both are self-hostable with no licence fee.
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
| Zen Browser | extism | |
|---|---|---|
| GitHub stars | ★ 44K | ★ 5.8K |
| License | MPL-2.0 | BSD-3-Clause |
| Written in | C++ | Rust |
| Last push | 2026-09-17 | 2026-09-02 |
| Forks | ⑂ 1.8K | ⑂ 168 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Zen Browser if
- You weight community size — 44K stars and counting
- You want the MPL-2.0 license terms
- Your stack matches C++
- You value the larger contributor base for long-term maintenance
pick extism if
- You want the extism feature set and don't need the biggest community
- You prefer the BSD-3-Clause license terms
- Your stack matches Rust
- You evaluated both and extism fits your workflow better
About Zen Browser
Zen Browser is a privacy focused, open source web browser built on Firefox’s Gecko engine. It inherits Firefox’s compatibility and extension ecosystem while introducing a streamlined interface and productivity oriented features. The project lives in the desktop browser ecosystem, targeting users who want a Firefox based experience with reduced clutter and enhanced customization.
read the full Zen Browser overview →
About extism
Extism is a lightweight, BSD 3 Clause licensed framework for running WebAssembly (Wasm) inside your own application, aimed at developers who want to make software extensible with untrusted, user supplied plug in code across servers, the edge, CLIs, IoT devices, and browsers.
read the full extism overview →
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Frequently asked questions
Is Zen Browser or extism more popular?
Zen Browser has 44,486 GitHub stars and extism has 5,764. Zen Browser has the larger community by that measure.
Are Zen Browser and extism free?
Both are open source. Zen Browser is licensed under MPL-2.0 and extism under BSD-3-Clause. Neither carries a licence fee.
What is the difference between Zen Browser and extism?
Zen Browser is written in C++ and extism in Rust. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Zen Browser or extism?
Choose Zen Browser if you want the larger community (44,486 stars) or its MPL-2.0 licence terms. Choose extism if its feature set, stack or BSD-3-Clause licence fits better. Both are self-hostable.