# Reddit Posts

---

## r/webdev

**Title:** Built an HTML-to-PDF API — looking for feedback on the API design

**Body:**

Hey r/webdev,

I've been working on a small API service called [DocFast](https://docfast.dev) that converts HTML or Markdown to PDF. The idea came from rebuilding the same Puppeteer-based PDF pipeline across multiple projects.

The basic idea: POST your HTML, get a PDF back. It also has built-in templates for common docs like invoices so you can just pass JSON data instead of writing HTML.

Quick example:

```javascript
const res = await fetch('https://docfast.dev/v1/convert/html', {
  method: 'POST',
  headers: {
    'Authorization': 'Bearer YOUR_KEY',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    html: '<h1>Hello</h1><p>This becomes a PDF.</p>',
    options: { format: 'A4' }
  })
});
```

There's a free tier (100 PDFs/month, no credit card) if anyone wants to try it.

I'm specifically looking for feedback on:
- The API design — does the interface feel intuitive?
- What templates would be most useful? (Currently have invoice, receipt, report)
- Anything you'd expect from a PDF API that's missing?

Docs are at https://docfast.dev/docs. Happy to answer any questions about the architecture too (Express + Puppeteer with a browser pool).

---

## r/node

**Title:** Managing a Puppeteer browser pool for PDF generation — lessons learned

**Body:**

I built an API service ([DocFast](https://docfast.dev)) that generates PDFs from HTML using Puppeteer, and wanted to share some things I learned about running Puppeteer in production with Node.

**The problem:** Launching a new Chromium instance per request is slow (~2-3s). For an API that needs to respond quickly, that's not acceptable.

**The solution:** A browser pool. I keep a set of warm Chromium instances and create new *pages* (not browsers) per request. New page creation takes ~50ms vs seconds for a cold browser launch.

Key things I learned:

1. **Memory management matters.** Each Chromium instance uses 100-300MB. You need to cap your pool size based on available memory and restart instances periodically to avoid leaks.

2. **Page cleanup is critical.** After each PDF generation, you need to properly close the page and clean up listeners. Forgetting this leads to slow memory leaks that only show up after hours of traffic.

3. **Graceful degradation.** If all pooled instances are busy, you have two choices: queue the request or spin up a temporary instance. I went with queuing + a small overflow pool.

4. **Font rendering is OS-dependent.** The same HTML can look different depending on what fonts are installed on the host system. I ended up bundling a standard set of fonts in the Docker image.

The API is live at https://docfast.dev if anyone wants to poke at it (free tier, 100 PDFs/mo). But mostly curious if others have dealt with similar Puppeteer pooling challenges and what approaches worked for you.