Story
Claude Code uses Bun written in Rust now
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1 website
1 discussion
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Overview
Claude Code v2.1.181 and later utilize the Rust port of Bun, resulting in a 10% faster startup on Linux. The command `strings ~/.local/bin/claude | grep -m1 'Bun v1'` confirms the use of Bun v1.4.0 on macOS.
Summary from simonwillison.net.
Reports
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simonwillison.net
Claude Code uses Bun written in Rust now
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Community reactions
Each reaction summarizes sampled comments from the linked discussion.
Hacker News · simonwillison.net
Hacker News discussion ↗
Historical count: 5 · 5 saved in sample · Historical sample
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Based on 5 sampled comments from this thread. Analyzed 2026-07-19.
- Praise: The ability to build and use the new Bun version from the public PR shows some transparency in the development process, allowing developers to experiment.
- Praise: The integration of Rust could potentially lead to performance improvements in the long run, even if the initial rollout is rocky.
- Concern: The switch to Rust feels like a death knell for Bun, with concerns about governance and transparency leaving users in the dark about the project's future.
- Concern: Many commenters question why anyone would switch to Bun, citing performance issues and a lack of compliance that make it a risky choice.
- Concern: The communication around the changes has been poor, damaging trust and creating divisions within the community.