MicroQuickJS
Ranked 3 of 6 JavaScript engines by recommenders
Tiny JavaScript engine for microcontrollers and embedding, praised for its small memory use and sandboxing. Main caveat: it implements only a subset of JavaScript close to ES5.
14 people recommended MicroQuickJS in Hacker News comments, 4 had mixed feelings and 7 criticized it, November 2025 to October 2026.
11 of the 14 people who recommend it commented in one thread, “Fabrice Bellard Releases MicroQuickJS”.
Summary written by Claude from 26 comments. It was written before the November 2026 recount, and 25 of those comments still count.
25 people gave an opinion
- recommend it
- 14
- mixed feelings
- 4
- warn against or regret it
- 7
The record
Recommended in 3 of 12 months
In 5 different threads.
- November 2025: not recommended
- December 2025: recommended
- January 2026: recommended
- February 2026: recommended
- March 2026: not recommended
- April 2026: not recommended
- May 2026: not recommended
- June 2026: not recommended
- July 2026: not recommended
- August 2026: not recommended
- September 2026: not recommended
- October 2026: not recommended
Why it doesn’t carry the badge
- 14 people recommend itNeeds 10 or more, met.
- 2 recommenders for every criticNeeds 2 to 1 or better, met.
- Recommended in 3 of 12 monthsNeeds 4 or more, not met.
- Recommended in 5 threadsNeeds 5 or more, met.
- 11 of its 14 recommenders came from one threadNeeds half or less, not met.
The same rules apply to every product, and the badge can’t be bought. Mixed feelings count toward neither side. How the badge works
What people say about it
Reasons grouped from a sample of 25 of the 31 opinions about it, picked in proportion to how many people recommend it, have mixed feelings and criticize it. Each mark is one comment in the sample. Open a reason to read what they said.
Why people recommend it
Each mark is one comment
Very small memory footprint
“Needing only 10K of RAM, it looks like a much better solution to CircuitPython”
Comment from 23 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS” “would be a killer replacement for micro/circuitpython for embedded devices”
Comment from 23 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS” “the fact that he can optimize a js engine down to 10kb of ram is wild”
Comment from 24 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS” Restricted subset avoids unneeded features
“none of the things which are impossible in this subset are things I would do in the course of normal programming anyway”
Comment from 23 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS” “restricting it this way for embedded systems will result in something that sparks joy”
Comment from 23 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS” “I'm really happy to see the stricter mode”
Comment from 24 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS” Easy to embed in existing software
“If you have some software that’s somewhat rigid you could make it scriptable by linking microquickjs.”
Comment from 25 Dec 2025 in “Ask HN: Good uses cases for Fabrice's microquickjs” “quickjs/mquickjs are good at embedding but nowhere close to luajit in terms of speed”
Comment from 14 Feb 2026 in “Vim 9.2 Released” Sandboxing with memory and time limits
“a useful sandbox in that you can robustly limit both the memory and time allowed”
Comment from 23 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS” “shouldn't be escapable, in theory, given the memory model”
Comment from 5 Jan 2026 in “JavaScript engines zoo – Compare every JavaScript engine”
What people warn about
Each mark is one comment
Only a subset of ES5
“I don't think you can transpile arbitrary TS in mqjs's JS subset.”
Comment from 23 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS” “it's not a full implementation of even ES5”
Comment from 23 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS”
Other JavaScript engines people recommend
The four most recommended other JavaScript engines, with the same counts for each, so you can compare like for like. The tick on each bar marks the 2 to 1 line the badge needs.
| Product | Recommend | Mixed | Criticize | Approval | Months | Had for | Badge |
|---|---|---|---|---|---|---|---|
| V8 JavaScript engine | 39 | 17 | 33 | 54% | 11 | — | — |
| QuickJS | 24 | 7 | 6 | 80% | 8 | — | Approved |
| MicroQuickJSThis page | 14 | 4 | 7 | 67% | 3 | — | — |
| Boa JavaScript engine | 9 | 5 | 4 | 69% | 2 | — | — |
| JavaScriptCore | 8 | 6 | 4 | 67% | 7 | — | — |
What people said
25 of the 31 opinions about it, picked in proportion to the three counts, newest first. Each links to the original comment.
“I have one for MicroQuickJS too”
“quickjs/mquickjs are good at embedding but nowhere close to luajit in terms of speed”
“shouldn't be escapable, in theory, given the memory model”
“appear to be my best options”
“If you have some software that’s somewhat rigid you could make it scriptable by linking microquickjs.”
“It's a good _start_; much more code needs to be written”
“the fact that he can optimize a js engine down to 10kb of ram is wild”
“I'm really happy to see the stricter mode”
“Looks like the real "JavaScript: The Good Parts”
“it’s a really interesting use case”
“it always returns 0 for your microquickjs version”
“This is a hell of a Christmas present”
“it seems like a lot of String functions I use are missing too”
“I don't think you can transpile arbitrary TS in mqjs's JS subset.”
“it's not a full implementation of even ES5”
“would be a killer replacement for micro/circuitpython for embedded devices”
“that would be an issue in many projects”
“Needing only 10K of RAM, it looks like a much better solution to CircuitPython”
“this is super cool, and I continue to be amazed by Fabrice”
“looks like a crossbar of random things that don't seem like things anyone would actually want to do”
“a useful sandbox in that you can robustly limit both the memory and time allowed”
“Glad to see a project of Fabrice Bellard on github, finally.”
“none of the things which are impossible in this subset are things I would do in the course of normal programming anyway”
“restricting it this way for embedded systems will result in something that sparks joy”
“MicroQuickJS looked like a very strong contender on that front”
Counts come from 1,791,911 Hacker News comments labeled by Claude, November 2025 to October 2026, with data through October 31, 2026. Counts updated 2 Nov 2026. How we count. Report a mistake.