QuickJS
Hacker ApprovedRanked 2 of 7 JavaScript engines by recommenders
Small, self-contained, fast C JavaScript engine by Fabrice Bellard that matches almost all of ES2025 and is easy to embed. Critics say it is much slower than JIT engines such as V8.
Small, self-contained, fast C JavaScript engine by Fabrice Bellard that matches almost all of ES2025 and is easy to embed. Critics say it is much slower than JIT engines such as V8.
41 people gave an opinion
- recommend it
- 33
- criticize it
- 8
- approval share
- 80%
Recommended in 10 of 13 months
- November 2025: recommended
- December 2025: recommended
- January 2026: recommended
- February 2026: recommended
- March 2026: recommended
- April 2026: recommended
- May 2026: not recommended
- June 2026: recommended
- July 2026: recommended
- August 2026: not recommended
- September 2026: recommended
- October 2026: recommended
- November 2026: not recommended (month in progress)
Why it carries the badge
- 33 people recommend itNeeds 10 or more, met.
- 4.1 recommenders for every criticNeeds 2 to 1 or better, met.
- Recommended in 10 of 13 monthsNeeds 4 or more, met.
The same three rules apply to every product, and the badge can’t be bought. How the badge works
What people say about it
The reasons people give, with the number of comments that give each one. Open a reason to read what they said.
Why people recommend it
Each mark is one comment
Small and lightweight, low resource use
“Hermes and QuickJS both come out looking very good in these (in terms of performance vs. binary size)”
Comment from 16 Nov 2025 in “Brimstone: ES2025 JavaScript engine written in Rust” “use a lightweight runtime (QuickJS or even the new Micro QuickJS)”
Comment from 28 Dec 2025 in “Show HN: Minfern – Type inference for JavaScript without transpilation” “QuickJS and LLRT which use like 1000x less resources than v8”
Comment from 2 Oct 2026 in “Pi 1.0” - Comment from 9 Oct 2026 in “Cloudflare acquires Deno”
- Comment from 6 Apr 2026 in “LÖVE: 2D Game Framework for Lua”
Simple, portable pure C code
“I was amazed to discover he created the entirety of JavaScript in a single xxx thousand line C file”
Comment from 23 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS” “it only takes a few seconds at worst. That's great news for portability!”
Comment from 13 Nov 2025 in “Yt-dlp: External JavaScript runtime now required for full YouTube support” “which is written in pure C and should work on anything”
Comment from 12 Nov 2025 in “Yt-dlp: External JavaScript runtime now required for full YouTube support” - Comment from 7 Nov 2025 in “Rapid Engine – game engine with a node-based programming language”
Embeddable and self-contained
“It's pretty handy for things like untrusted user authored JS scripts that run on a user's client.”
Comment from 24 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS” “embeddable, self contained (no libs) and fast JavaScript engine matching almost entirely ES2025”
Comment from 16 Jun 2026 in “John Carmack on Fabrice Bellard” “I easily managed to build quickJS to WebAssembly for running in exaequOS.com”
Comment from 23 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS” Performance adequate for embedding
“Hermes and QuickJS both come out looking very good in these (in terms of performance vs. binary size)”
Comment from 16 Nov 2025 in “Brimstone: ES2025 JavaScript engine written in Rust” “performed more than adequately for the kind of thing this class of software needs”
Comment from 1 Oct 2026 in “Pi 1.0” “A 5x slowdown for an interpreted C JS engine is pretty good I think”
Comment from 12 Nov 2025 in “Yt-dlp: External JavaScript runtime now required for full YouTube support”
What people warn about
Each mark is one comment
Much slower than JIT engines
“Quickjs (despite being pretty good) can't match the performance of sophisticated JIT implementations like V8 or JavaScriptCore”
Comment from 24 Dec 2025 in “Fabrice Bellard Releases 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” “QuickJS also pays a performance tax (no JIT) and still doesn't give you the OS”
Comment from 8 Jun 2026 in “Running Python code in a sandbox with MicroPython and WASM” - Comment from 21 Apr 2026 in “How to Make a Fast Dynamic Language Interpreter”
- Comment from 27 Jul 2026 in “Scriptc by Vercel: TypeScript-to-Native compiler, no JavaScript engine in binary”
Weak as a security sandbox
“how extremely weak a C executable like QuickJS is for LLMs to exploit”
Comment from 19 Jan 2026 in “On The Coming Industrialisation of Exploit Generation with LLMs” “not trusting that as a sandbox to the same degree”
Comment from 23 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS” Slow on old hardware or wasm
“Even Edbrowse can grind down to a halt an n270 netbook because of some sites with JS (both with qjs and qjs-ng).”
Comment from 24 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS” “You lose a non-trivial amount of performance running js inside quickjs inside of wasm”
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 | Criticize | Approval | Months | Owned | Badge |
|---|---|---|---|---|---|---|
| V8 JavaScript engine | 59 | 36 | 62% | 12 | — | — |
| QuickJSThis page | 33 | 8 | 80% | 10 | — | Approved |
| MicroQuickJS | 19 | 8 | 70% | 3 | — | — |
| JavaScriptCore | 14 | 5 | 74% | 9 | — | Approved |
| Boa JavaScript engine | 14 | 7 | 67% | 3 | — | — |
What people said
34 of the 49 comments that mention it, newest first. Each links to the original comment.
“why not use an existing effort that works?”
“QuickJS works fine for yt-dlp and is way smaller”
“QuickJS and LLRT which use like 1000x less resources than v8”
“performed more than adequately for the kind of thing this class of software needs”
“they will be falling off into quickjs a lot”
“quickjs-ng is no better than quickjs”
“Quickjs is hilariously slow.”
“embeddable, self contained (no libs) and fast JavaScript engine matching almost entirely ES2025”
“QuickJS also pays a performance tax (no JIT) and still doesn't give you the OS”
“Because QuickJS is really slow.”
“QuickJS, which is also lightweight”
“can work with V8, Javascript, SpiderMonkey, QuickJS, Hermes, etc.”
“quickjs/mquickjs are good at embedding but nowhere close to luajit in terms of speed”
“how extremely weak a C executable like QuickJS is for LLMs to exploit”
“full QuickJS running inside WebAssembly do appear to be my best options”
“use a lightweight runtime (QuickJS or even the new Micro QuickJS)”
“many other brilliant and fascinating tools!”
“bellard is basically proof that the "10x engineer" exists. ffmpeg, qemu, quickjs”
“Even Edbrowse can grind down to a halt an n270 netbook because of some sites with JS (both with qjs and qjs-ng).”
“It's pretty handy for things like untrusted user authored JS scripts that run on a user's client.”
“Quickjs (despite being pretty good) can't match the performance of sophisticated JIT implementations like V8 or JavaScriptCore”
“not trusting that as a sandbox to the same degree”
“You lose a non-trivial amount of performance running js inside quickjs inside of wasm”
“I was amazed to discover he created the entirety of JavaScript in a single xxx thousand line C file”
“I easily managed to build quickJS to WebAssembly for running in exaequOS.com”
“so cool that QuickJS enabled an old system like PS2 to have a bit of a homebrew revival”
“Hermes and QuickJS both come out looking very good in these (in terms of performance vs. binary size)”
“they are limited in specification conformance or at least selective in specification conformance”
“pin down the ecma262 revision and make it 100% compliant”
“QuickJS (which is also supported by GodotJS) is probably the safer bet.”
“it only takes a few seconds at worst. That's great news for portability!”
“A 5x slowdown for an interpreted C JS engine is pretty good I think”
“which is written in pure C and should work on anything”
“it is coded in plain and simple C”
Counts come from 1,795,640 Hacker News comments, November 2025 to November 2026. How we count. Report a mistake.