Last Updated on February 27, 2026
QuickJS is a small and embeddable JavaScript engine. It supports the ES2023 specification including modules, asynchronous generators, proxies and BigInt.
It optionally supports mathematical extensions such as big decimal floating point numbers (BigDecimal), big binary floating point numbers (BigFloat) and operator overloading.
This is free and open source software.
Key Features
- Small and easily embeddable: just a few C files, no external dependency, 210 KiB of x86 code for a simple hello world program.
- Fast interpreter with very low startup time: runs the 76000 tests of the ECMAScript Test Suite in less than 2 minutes on a single core of a desktop PC. The complete life cycle of a runtime instance completes in less than 300 microseconds.
- Almost complete ES2023 support including modules, asynchronous generators and full Annex B support (legacy web compatibility).
- Passes nearly 100% of the ECMAScript Test Suite tests when selecting the ES2023 features. A summary is available at Test262 Report.
- Can compile JavaScript sources to executables with no external dependency.
- Garbage collection using reference counting (to reduce memory usage and have deterministic behavior) with cycle removal.
- Mathematical extensions: BigDecimal, BigFloat, operator overloading, bigint mode, math mode.
- Command line interpreter with contextual colorization implemented in JavaScript.
- Small built-in standard library with C library wrappers.
Website: bellard.org/quickjs
Support: GitHub Code Repository
Developer: Fabrice Bellard, Charlie Gordon
License: MIT License
QuickJS is written in C. Learn C with our recommended free books and free tutorials.
Related Software
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|---|---|
| V8 | High-performance JavaScript and WebAssembly engine |
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| QuickJS | Small and embeddable Javascript engine |
| Hermes | JavaScript engine optimized for React Native |
| JerryScript | JavaScript engine for the Internet of Things |
| Duktape | Embeddable JavaScript engine, focusing on portability and compact footprint |
| Elk | Tiny embeddable JavaScript engine |
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