head to head · open source
uBlock vs opal
uBlock has 67,937 GitHub stars, 4,354 forks, 15 open issues and last shipped yesterday. opal has 4,926 stars, 336 forks, 152 open issues and last shipped 5 days ago. uBlock leads on adoption by 1,279% (67,937 vs 4,926 stars). uBlock is written in JavaScript under GPL-3.0; opal is written in Ruby under MIT. uBlock has attracted 6% as many forks as stars, opal 7%. 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 | opal | |
|---|---|---|
| GitHub stars | ★ 68K | ★ 4.9K |
| License | GPL-3.0 | MIT |
| Written in | JavaScript | Ruby |
| Last push | 2026-09-17 | 2026-09-13 |
| Forks | ⑂ 4.4K | ⑂ 336 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick uBlock if
- You weight community size — 68K 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 opal if
- You want the opal feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches Ruby
- You evaluated both and opal fits your workflow better
About uBlock
uBlock Origin is a CPU and memory efficient, wide spectrum content blocker for Chromium and Firefox, aimed at anyone who wants ads, trackers, coin miners, popups, anti blockers and malware sites neutralised by default without hand tuning anything.
read the full uBlock overview →
About opal
Opal is an MIT licensed Ruby to JavaScript source to source compiler, distributed as a Ruby gem, that lets developers write Ruby and run the resulting JavaScript in the browser, Node.js, Deno, Bun, or QuickJS.
More in Productivity & Utilities
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Frequently asked questions
Is uBlock or opal more popular?
uBlock has 67,937 GitHub stars and opal has 4,926. uBlock has the larger community by that measure.
Are uBlock and opal free?
Both are open source. uBlock is licensed under GPL-3.0 and opal under MIT. Neither carries a licence fee.
What is the difference between uBlock and opal?
uBlock is written in JavaScript and opal in Ruby. 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 opal?
Choose uBlock if you want the larger community (67,937 stars) or its GPL-3.0 licence terms. Choose opal if its feature set, stack or MIT licence fits better. Both are self-hostable.