Why serverless Chromium is so painful on Vercel and Lambda

The four failure modes

Almost every "generate a PDF in a serverless function" project hits the same wall. It works locally, then breaks in production for one of four reasons.

1. **Bundle size.** A full Chromium is ~150 MB. Vercel/Lambda cap the deployed function. @sparticuz/chromium ships a stripped, compressed build to fit — but you have to wire it correctly and it is easy to bloat past the limit again.
2. **Cold starts.** The browser binary has to be decompressed and launched on the first request after a scale-up. That is multiple seconds before a single byte renders.
3. **Missing system libraries.** Chromium links against fonts and shared libraries (libnss3, libatk, emoji/CJK fonts) that aren't in the minimal serverless image. Miss one and you get a blank page or a launch crash.
4. **Timeouts.** A cold start plus a heavy render can blow past the function's max duration, so the render dies half-finished with an opaque 502.

Why local works but prod doesn't

Locally you have the full system Chromium, all fonts, no bundle limit, and no cold start. The serverless runtime strips all four away at once, so the same code that renders a clean invoice on your laptop returns a blank or broken PDF in production.

The pragmatic fixes

• **Warm, dedicated worker.** Keep one long-lived process with a launched browser and send it render jobs. No cold start, no bundle limit. This is what most teams graduate to.
• **Hosted PDF API.** Offload the whole problem: one HTTP call in, a PDF out. No Chromium in your bundle at all. See generate a PDF from any stack.

Docweave runs Chromium on a warm worker behind an API, so your function just makes one request. If you want to keep rendering yourself, at least move it off the request path onto a warm process — the four failure modes above all trace back to launching a browser inside a cold, stripped sandbox.

A one-call alternative

If you'd rather not manage any of this, send HTML and get a PDF back:

curl https://docweave.dev/api/v1/pdf \
  -H "Authorization: Bearer dw_live_your_key" \
  -H "Content-Type: application/json" \
  -H "Accept: application/pdf" \
  -d '{"source":{"type":"html","html":"<h1>Invoice #1024</h1>"}}' \
  --output invoice.pdf