Bun on Vercel Functions now supports 5GB packages and 30-minute durations

Vercel has extended two of its long-running compute capabilities to the Bun runtime on Vercel Functions: packages of up to 5GB uncompressed and function durations of up to 30 minutes. According to Vercel's changelog, both features were previously available as betas only for the Node.js and Python runtimes.

The new limits

The large functions beta raises the standard package size ceiling from 250MB to 5GB uncompressed, a twentyfold increase in headroom for deployments that need to ship large dependency trees or bundled assets alongside their code.

The extended max duration beta raises the generally available ceiling of 800 seconds to 1800 seconds, a full 30 minutes. Vercel notes that durations beyond the standard ceiling are available to Pro and Enterprise teams. Both features require Fluid compute to be enabled on the project.

How to opt in

New projects are enrolled in the large functions beta automatically. Existing projects created before July 2026 opt in by adding VERCEL_SUPPORT_LARGE_FUNCTIONS=1 as an environment variable in project settings and then redeploying.

Durations above 800 seconds are configured per function rather than as a project-level default, via the maxDuration field in vercel.:

{ "functions": { "server.ts": { "maxDuration": 1800 } } }

The long-running route itself is handled by an ordinary Bun server entry point, using Bun.serve and its routes map:

ts Bun.serve({ routes: { "/": () => Response.({ success: true }) } });

Beta limitations

While the features are in beta, they are unavailable on projects that use Secure Compute or Static IPs. Vercel publishes the full details in its large functions and extended max duration documentation.

Why it matters

Bun's pitch on the server has been speed: fast startup, an integrated bundler and test runner, and broad compatibility with Node.js APIs. But on a serverless platform, the runtime is only part of the equation. A 250MB package cap and a ceiling of roughly 13 minutes constrained what a Bun function could realistically do, and until now Node.js and Python users on Vercel had beta access to higher limits that Bun users did not. That gap has closed.

The combination of 5GB packages and 30-minute execution windows moves Bun on Vercel beyond short-lived request handlers into longer jobs: batch processing, media pipelines, or any workload that needs to carry bulky dependencies with the code. Because the extended duration is set per function, teams can keep fast, cheap functions for ordinary traffic and reserve the 30-minute ceiling for the specific entry points that need it.

There are strings attached: Fluid compute must be on, longer durations are limited to Pro and Enterprise plans, and Secure Compute and Static IPs projects are excluded for now. For teams outside those constraints, though, the practical ceiling for running Bun in production on Vercel just rose considerably.