--- title: Claude Code uses Bun written in Rust now | daily.dev description: Claude Code v2.1.181 and later versions ship with a Rust-based port of Bun, confirmed by Simon Willison through binary inspection of his local Claude... canonical: https://daily.dev/posts/claude-code-uses-bun-written-in-rust-now-sxbybasdo twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Claude Code uses Bun written in Rust now | daily.dev og:description: Claude Code v2.1.181 and later versions ship with a Rust-based port of Bun, confirmed by Simon Willison through binary inspection of his local Claude... og:url: https://daily.dev/posts/claude-code-uses-bun-written-in-rust-now-sxbybasdo og:image: https://api.daily.dev/og/posts/SXbYBaSDo.png og:image:alt: Claude Code uses Bun written in Rust now og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Claude Code uses Bun written in Rust now **[Hacker News](https://daily.dev/sources/hn)** · 2 min read · 0 upvotes · 0 comments ## Summary Claude Code v2.1.181 and later versions ship with a Rust-based port of Bun, confirmed by Simon Willison through binary inspection of his local Claude installation. Using `strings` commands, he found Bun v1.4.0 (a pre-release version ahead of the public v1.3.14) and 563 Rust source file references embedded in the binary. The migration resulted in a 10% faster startup on Linux, with the change going largely unnoticed by users — a sign of a smooth, low-disruption rewrite. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: --- Tags: [#rust](https://daily.dev/tags/rust), [#anthropic](https://daily.dev/tags/anthropic), [#claude-code](https://daily.dev/tags/claude-code), [#bun](https://daily.dev/tags/bun) [View this post on daily.dev](https://daily.dev/posts/claude-code-uses-bun-written-in-rust-now-sxbybasdo) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Claude Code uses Bun written in Rust now","url":"https://daily.dev/posts/claude-code-uses-bun-written-in-rust-now-sxbybasdo","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/claude-code-uses-bun-written-in-rust-now-sxbybasdo"},"datePublished":"2026-07-19T10:59:59.265Z","dateModified":"2026-07-20T09:05:28.279Z","description":"Claude Code v2.1.181 and later versions ship with a Rust-based port of Bun, confirmed by Simon Willison through binary inspection of his local Claude...","image":"https://media.daily.dev/image/upload/s--58gMhC4P--/f_auto/v1722860399/public/Placeholder%2012","thumbnailUrl":"https://media.daily.dev/image/upload/s--58gMhC4P--/f_auto/v1722860399/public/Placeholder%2012","isAccessibleForFree":true,"articleSection":"Hacker News","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Hacker News","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/hn","url":"https://daily.dev/sources/hn"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/claude-code-uses-bun-written-in-rust-now-sxbybasdo","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"rust,anthropic,claude-code,bun","timeRequired":"PT2M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Hacker News","item":"https://daily.dev/sources/hn"},{"@type":"ListItem","position":3,"name":"Claude Code uses Bun written in Rust now"}]} ```