head to head · open source
uBlock vs extism
uBlock has 69,033 GitHub stars, 4,427 forks, 15 open issues and last shipped yesterday. extism has 5,823 stars, 167 forks, 54 open issues and last shipped 25 days ago. uBlock leads on adoption by 1,086% (69,033 vs 5,823 stars). uBlock is written in JavaScript under GPL-3.0; extism is written in Rust under BSD-3-Clause. uBlock has attracted 6% as many forks as stars, extism 3%. uBlock was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (javascript), 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
| uBlock | extism | |
|---|---|---|
| GitHub stars | ★ 69K | ★ 5.8K |
| License | GPL-3.0 | BSD-3-Clause |
| Written in | JavaScript | Rust |
| Last push | 2026-11-02 | 2026-10-09 |
| Forks | ⑂ 4.4K | ⑂ 167 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick uBlock if
- You weight community size — 69K stars and counting
- You want the GPL-3.0 license terms
- Your stack matches JavaScript
- 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 uBlock
[![Badge Commits]][Commit Rate] [![Badge Issues]][Issues] [![Badge Localization]][Crowdin] [![Badge License]][License] [![Badge NPM]][NPM] [![Badge Mozilla]][Mozilla] ![Badge Chrome] [![Badge Edge]][Edge] uBlock Origin (uBO) GitHub Releases Stable and development versions on Firefox, Chromium MV2, and Thunderbird. Must be placed manually into web browsers; the Chromium and Thunderbird versions usually won't auto update. Related: uBlock Origin Lite uBlock Origin (uBO) is a CPU and memory efficient [wide spectrum content blocker][Blocking] for Chromium and Firefox. It blocks ads, trackers, coin miners, popups…
read the full uBlock overview →
About extism
Overview Extism is a lightweight framework for building with WebAssembly (Wasm). It supports running Wasm code on servers, the edge, CLIs, IoT, browsers and everything in between. Extism is designed to be "universal" in that it supports a common interface, no matter where it runs. Note: One of the primary use cases for Extism is building extensible software & plugins . You want to be able to execute arbitrary, untrusted code from your users? Extism makes this safe and practical to do. Additionally, Extism adds some extra utilities on top of standard Wasm runtimes. For example, we support persistent memory/module…
read the full extism overview →
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Frequently asked questions
Is uBlock or extism more popular?
uBlock has 69,033 GitHub stars and extism has 5,823. uBlock has the larger community by that measure.
Are uBlock and extism free?
Both are open source. uBlock is licensed under GPL-3.0 and extism under BSD-3-Clause. Neither carries a licence fee.
What is the difference between uBlock and extism?
uBlock is written in JavaScript 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, uBlock or extism?
Choose uBlock if you want the larger community (69,033 stars) or its GPL-3.0 licence terms. Choose extism if its feature set, stack or BSD-3-Clause licence fits better. Both are self-hostable.