# Bun 1.4 is now available in Vercel Functions

DevFeed: [Bun 1.4 is now available in Vercel Functions](<https://devfeed.tech/articles/bun-1-4-is-now-available-in-vercel-functions-829.md>)

Original publisher: [Read original article](<https://vercel.com/changelog/bun-1-4-is-now-available-in-vercel-functions>)

Author: Tom Lienard

Published: 2026-08-20T00:00:00Z

Content type: release

Language: en

Sources: [Vercel News](<https://devfeed.tech/sources/vercel-news.md>)

Topics: [Bun](<https://devfeed.tech/topics/bun.md>), [Vercel](<https://devfeed.tech/topics/vercel.md>), [Rust](<https://devfeed.tech/topics/rust.md>), [Node.js](<https://devfeed.tech/topics/node-js.md>), [WebSocket](<https://devfeed.tech/topics/websocket.md>), [Zig](<https://devfeed.tech/topics/zig.md>), [Hono](<https://devfeed.tech/topics/honojs.md>), [Next.js](<https://devfeed.tech/topics/next-js.md>)

Tags: [2](<https://devfeed.tech/tags/2.md>), [bun](<https://devfeed.tech/tags/bun.md>), [compatibility](<https://devfeed.tech/tags/compatibility.md>), [compute](<https://devfeed.tech/tags/compute.md>), [cpu](<https://devfeed.tech/tags/cpu.md>), [features](<https://devfeed.tech/tags/features.md>), [frameworks](<https://devfeed.tech/tags/frameworks.md>), [next-js](<https://devfeed.tech/tags/next-js.md>), [node](<https://devfeed.tech/tags/node.md>), [node-js](<https://devfeed.tech/tags/node-js.md>), [performance](<https://devfeed.tech/tags/performance.md>), [release](<https://devfeed.tech/tags/release.md>), [rust](<https://devfeed.tech/tags/rust.md>), [support](<https://devfeed.tech/tags/support.md>), [update](<https://devfeed.tech/tags/update.md>), [vercel](<https://devfeed.tech/tags/vercel.md>), [zig](<https://devfeed.tech/tags/zig.md>)

## AI overview

Vercel Functions now support Bun 1.4, which rewrites Bun from Zig to Rust and includes resolved issues, additional Node.js compatibility tests, new features, and performance improvements. Bun runs on Fluid compute, supports Active CPU pricing and WebSockets, and works with frameworks including Next.js and Hono. Upgrading is an explicit opt-in because of breaking changes.

## Source excerpt

Vercel Functions now support the new Bun 1.4 release, a rewrite of Bun from Zig to Rust, with over 2,900 issues resolved, more than 1,500 additional Node.js compatibility tests passing, and new features and performance improvements. Bun on Vercel Functions: Runs on Fluid compute with Active CPU pricing Supports WebSockets and Bun.serve() Supports common frameworks such as Next.js, Elysia, and Hono To update from the previous Bun version, set bunVersion to 1.4.x in vercel.json. Upgrading is an explicit opt-in because Bun 1.4 has several breaking changes. Review the breaking changes and update your application before upgrading. Learn more about using Bun on Vercel in the runtime documentation. Read more