# Bun 1.4 is now available in Vercel Functions

By Steven Van · 2026-08-20

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…

Vercel Functions now support [Bun 1.4](<https://vercel.com/changelog/bun-1-4-is-now-available-in-vercel-functions>), a rewrite of Bun from Zig to Rust that resolves over 2,900 issues and passes more than 1,500 additional Node.js compatibility tests. On [Vercel](<https://creatorstoolbox.com/tools/vercel>), Bun runs on Fluid compute with Active CPU pricing, supports WebSockets and Bun.serve(), and works with frameworks such as Next.js, Elysia, and Hono.

Upgrading is opt-in: set **bunVersion** to 1.4.x in vercel.json. Bun 1.4 includes several breaking changes, so review them before switching over.

[![](<https://assets.vercel.com/image/upload/contentful/image/e5382hct74si/6e3YWYnLDgfcQsx5ZAKb7R/38595838daba222d9122c037ee3c63dd/bun-1-4-og.png>)](<https://vercel.com/changelog/bun-1-4-is-now-available-in-vercel-functions>)

![Vercel](<https://www.google.com/s2/favicons?domain=vercel.com&sz=128>)

Vercel

The platform for frontend developers — deploy, preview, and scale web apps and AI agents with zero config.

[View Vercel →](<https://creatorstoolbox.com/tools/vercel>)

Sources

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

[Read Bun 1.4 is now available in Vercel Functions on Creators Toolbox](<https://creatorstoolbox.com/blog/vercel-bun-1-4-is-now-available-in-vercel-functions>)

---
Canonical source: https://creatorstoolbox.com/blog/vercel-bun-1-4-is-now-available-in-vercel-functions