# Boa

> JavaScript engine written in Rust

**Wikidata**: [Q126868542](https://www.wikidata.org/wiki/Q126868542)  
**Source**: https://4ort.xyz/entity/boa-q126868542

## Summary
Boa is an open-source JavaScript engine written in the Rust programming language. It is licensed under the MIT License and Unlicense, making it free software that allows users to freely run, study, and modify the code. Boa is cross-platform software, capable of operating on multiple computing platforms.

## Key Facts
- **Entity Type:** JavaScript engine, open-source software, free software.
- **Programming Language:** Written in Rust.
- **Licenses:** MIT License, Unlicense (dedicated to the public domain).
- **Platform:** Cross-platform.
- **Aliases:** Boa JS, BoaJS.
- **Website:** https://boajs.dev/
- **Source Code:** https://github.com/boa-dev/boa
- **Latest Stable Version:** 0.21 (Release Date: 2025-10-21).
- **Social Media:** Mastodon (@boa_engine@fosstodon.org).

## FAQs
### Q: What programming language is Boa written in?
A: Boa is written in Rust. It is designed to be a JavaScript engine that benefits from Rust's safety and performance features.

### Q: Is Boa free to use?
A: Yes, Boa is free software. It is dual-licensed under the MIT License and the Unlicense, allowing for broad use, modification, and distribution.

### Q: What platforms does Boa support?
A: Boa is cross-platform software. It is designed to be implemented and operate on multiple computing platforms.

### Q: When was the most recent version of Boa released?
A: According to provided data, the stable version 0.21 was released on October 21, 2025.

## Why It Matters
Boa represents a significant development in the ecosystem of web technologies by implementing a JavaScript engine in Rust, a language known for its memory safety and concurrency features. While traditional JavaScript engines are often written in C++, Boa offers an alternative that leverages Rust's guarantees to prevent common programming errors, potentially leading to a more secure and stable execution environment for JavaScript.

As an open-source project licensed under permissive terms (MIT and Unlicense), Boa lowers the barrier to entry for developers wishing to embed a JavaScript engine into their Rust applications or contribute to the engine's development. Its active release schedule—documenting multiple stable releases between 2022 and 2025—demonstrates ongoing maintenance and evolution. This makes Boa a relevant tool for developers interested in modern systems programming, language tooling, and the intersection of Rust and JavaScript ecosystems.

## Notable For
- Being a JavaScript engine implemented entirely in **Rust**, distinguishing it from C++-based engines like V8 or SpiderMonkey.
- Operating under a dual-license model (**MIT License and Unlicense**), offering maximum flexibility for users and contributors.
- **Cross-platform compatibility**, ensuring it can run on various operating systems without restriction.
- **Active development**, evidenced by frequent stable releases (0.16 through 0.21) documented in recent years.

## Body

### Technical Overview
Boa is a JavaScript engine, which is a software component responsible for executing JavaScript code. Unlike web browsers that typically use engines written in C++, Boa is constructed using Rust. This classification places it within the categories of both free software and open-source software. It is designed to function as cross-platform software, meaning it is capable of operating on multiple computing platforms.

### Licensing and Copyright
The project is distinct for its permissive licensing structure. Boa is distributed under both the **MIT License** and the **Unlicense**. This dual-licensing allows users to choose either option, effectively dedicating the code to the public domain in some interpretations while maintaining a standard open-source license in others. It is classified as both "copyrighted" and "dedicated to the public domain by copyright holder."

### Version History
Development of Boa has resulted in numerous stable releases, showing a trajectory of ongoing updates:

- **v0.16:** Released September 25, 2022.
- **v0.17:** Released July 8, 2023.
- **v0.17.1:** Released September 26, 2023.
- **v0.17.3:** Released September 26, 2023.
- **v0.18:** Released March 7, 2024.
- **v0.19:** Released July 11, 2024.
- **v0.19.1:** Released September 12, 2024.
- **v0.20:** Released December 5, 2024.
- **v0.21:** Released October 21, 2025 (Identified as the preferred stable version in source data).

### Project Resources
The project maintains a strong online presence for developers and users:
- **Website:** Official documentation and information are hosted at `boajs.dev`.
- **Repository:** The source code is publicly available on GitHub under the user `boa-dev` at `github.com/boa-dev/boa`.
- **Community:** The project maintains a presence on the Mastodon social network at `boa_engine@fosstodon.org` (active since July 5, 2023).

## References

1. [Release 0.16. 2022](https://github.com/boa-dev/boa/releases/tag/v0.16)
2. [Release 0.17. 2023](https://github.com/boa-dev/boa/releases/tag/v0.17)
3. [Release 0.17.1. 2023](https://github.com/boa-dev/boa/releases/tag/v0.17.1)
4. [Release 0.17.3. 2023](https://github.com/boa-dev/boa/releases/tag/v0.17.3)
5. [Release 0.18. 2024](https://github.com/boa-dev/boa/releases/tag/v0.18)
6. [Release 0.19. 2024](https://github.com/boa-dev/boa/releases/tag/v0.19)
7. [Release 0.19.1. 2024](https://github.com/boa-dev/boa/releases/tag/v0.19.1)
8. [Release 0.20. 2024](https://github.com/boa-dev/boa/releases/tag/v0.20)
9. [Release 0.21. 2025](https://github.com/boa-dev/boa/releases/tag/v0.21)
10. [Release 0.21.1. 2026](https://github.com/boa-dev/boa/releases/tag/v0.21.1)