The video downloader 'yt-dlp' has deprecated Bun, due to concerns about the risks associated with Bun's over-reliance on AI coding.

When downloading YouTube videos with the video download tool ' yt-dlp, ' it is strongly recommended to install a JavaScript runtime such as 'Deno' or 'QuickJS.' Until now, 'Bun' was also supported, but it was announced on May 21, 2026, that Bun would be deprecated.

[Announcement] Bun support is now limited and deprecated · Issue #16766 · yt-dlp/yt-dlp
https://github.com/yt-dlp/yt-dlp/issues/16766

yt-dlp is a video download tool available for Windows, macOS, Linux, and other operating systems, allowing you to download videos from various websites with simple command-line operations. Until 2025, it was possible to download YouTube videos without additional software, but the old method has become incompatible with YouTube, so the system has changed to one that requires a JavaScript runtime such as Deno for downloading.

Finally, to fully utilize yt-dlp's YouTube download function, a JavaScript runtime such as Deno is required; here's how to install it - GIGAZINE

The yt-dlp development team has specified Deno as the recommended runtime, but has also supported runtimes such as QuickJS and Bun. However, on May 21, 2026, an announcement titled 'Currently, Bun support is limited and deprecated' was posted to the GitHub repository. According to the development team, only Bun versions 1.2.11 through 1.3.14 will be supported from now on, and older and newer versions of Bun will no longer be supported. Furthermore, Bun will be deprecated as a runtime.

The development team cites 'addressing security concerns' and 'concerns about Bun's development policies' as reasons for limiting support for Bun.

Bun is gaining attention as a fast JavaScript runtime, and in December 2025, its development team was acquired by the AI company Anthropic. Subsequently, in May 2026, it was announced that the Zig-based code was being migrated to a Rust-based version. At the time of writing this article, the Rust version of Bun is not yet in release, but the yt-dlp development team commented, 'Bun has been rewritten in Rust by Claude, and the development system seems to have completely shifted to vibe coding. Frankly speaking, Bun's change of direction is likely to become a headache for us in the future. For this reason, we will limit support to the last Zig-based version,' revealing that they are limiting support due to concerns that the code written by AI will become a cost in the future.

Furthermore, bashonly , a member of the development team, commented, 'I have dealt with code submissions written in LLM format as a maintainer of large-scale FOSS projects, and I am completely against them.' 'Unlike Bun, yt-dlp is developed and maintained entirely by volunteers without compensation.' 'I don't think this decision will be a problem. The majority of yt-dlp users either 'don't use Bun' or 'are not as interested as those who object to the discontinuation of Bun support.' Also, supporting Bun after it has been replaced by Rust is high-risk, while discontinuing support is not.'

You can check the progress of Bun's Rust migration at the following link.

Bun's unreleased Rust port has 13,365 unsafe blocks. Most can be removed.
https://bun.com/bun-unsafe-audit