HTML to PDF API Comparison 2026: pdfRelay vs DocRaptor vs PDFShift
A detailed comparison of the top HTML-to-PDF APIs — pricing, speed, features, and which one is right for your project.
The landscape in 2026
If you need to generate PDFs from HTML programmatically, you have three main options: run a headless browser yourself (Puppeteer, Playwright), use a dedicated rendering engine (Prince, WeasyPrint), or call an API (pdfRelay, DocRaptor, PDFShift).
Most teams start with Puppeteer because it's free. But as they scale, the operational burden — memory leaks, Docker images with Chromium, cold start latency — pushes them toward an API. The question becomes: which one?
pdfRelay vs DocRaptor
Engine: DocRaptor uses PrinceXML under the hood — a proprietary C++ engine. pdfRelay uses a custom Rust engine built from scratch. Both produce high-quality output, but pdfRelay's Rust engine is significantly faster (10-50x) because it doesn't need to spin up a browser.
Pricing: DocRaptor starts at $15/mo for 125 documents ($0.12/doc). pdfRelay starts at $29/mo for 500 documents with hosting and e-signatures included. At volume, the difference is dramatic: 5,000 documents costs $1,200/mo on DocRaptor vs $99/mo on pdfRelay Business.
Features DocRaptor lacks: Document hosting, e-signatures, React JSX templates, async/batch processing, webhooks. DocRaptor is purely a conversion API.
pdfRelay vs PDFShift
Engine: PDFShift uses Chromium (similar to Puppeteer) running on their servers. This means the same rendering inconsistencies and JavaScript dependency, just hosted for you.
Pricing: PDFShift starts at $9/mo for 500 credits. Similar per-document cost to pdfRelay, but without hosting, signing, or templates.
Key difference: PDFShift runs your HTML through a browser. pdfRelay renders it natively — no browser, no JavaScript execution, no Chromium binary. The result is faster, more predictable, and uses a fraction of the memory.
pdfRelay vs Puppeteer (DIY)
"Free" is Puppeteer's biggest advantage and biggest lie. It's free until you count the engineering time spent on:
- Configuring Chromium in Docker (600MB+ images)
- Managing browser process pools and memory limits
- Handling zombie processes, timeouts, and race conditions
- Debugging font rendering differences across environments
- Scaling horizontally with proper load balancing
An API eliminates all of this. pdfRelay costs $29/mo. A senior engineer's time costs $100+/hour. The math is straightforward.
The verdict
If you want the simplest, most cost-effective HTML-to-PDF solution with modern features (hosting, signing, templates), pdfRelay is the clear choice. If you're already deeply invested in PrinceXML's CSS support and don't need any features beyond conversion, DocRaptor is solid. If budget is your only concern, PDFShift works.
But here's what none of the competitors offer: you can write your documents in plain HTML — the language you already know — and add e-signatures with a simple <sign-field> element. No proprietary markup. No coordinate-based field placement. No separate signing service.