# pdf.js

10 Hacker News commenters recommended pdf.js and 4 criticized it, November 2025 to November 2026. It was recommended in 8 of 13 months. It meets the Hacker Approved badge rule.

**Verdict:** Free PDF viewer built into Firefox and many websites, praised as clean, minimal and mostly safe. Common caveat: slower and less capable with very large files and editing.

## Why people recommend it

- Built into Firefox and websites (2 comments): "It's what Firefox uses, and most websites with integrated on-page PDF viewing functionality." ([source](https://news.ycombinator.com/item?id=50282005)) "it's been a helpful JS library for embedding PDFs on websites" ([source](https://news.ycombinator.com/item?id=46713990))
- Mostly safe, sandboxed design (3 comments): "pdf.js is considered mostly safe, and updated." ([source](https://news.ycombinator.com/item?id=46319043)) "In theory, it's as safe as loading a webpage." ([source](https://news.ycombinator.com/item?id=46714388)) "a clean minimalist sandboxed PDF parser" ([source](https://news.ycombinator.com/item?id=48557410))
- Clean and uncluttered (2 comments): "Evince/PdfJS have way fewer buttons and clutter and pop-ups than the Adobe crap" ([source](https://news.ycombinator.com/item?id=47715752)) "a clean minimalist sandboxed PDF parser" ([source](https://news.ycombinator.com/item?id=48557410))

## What people warn about

- Slow with very large PDFs (2 comments): "It's still a slight performance regression for very giant pdf. But it is enough for most use case." ([source](https://news.ycombinator.com/item?id=45875536)) "using pdf.js wasn't gonna work and be too slow and the wrong interface anyway" ([source](https://news.ycombinator.com/item?id=47974415))
- Poor font support, can't edit images (2 comments): "problems such as poor font support and barely any way to change existing images" ([source](https://news.ycombinator.com/item?id=48816832)) "poor font support and barely any way to change existing images" ([source](https://news.ycombinator.com/item?id=48832931))

## Alternatives hackers recommend

- [Apple Preview](https://hackerapproved.com/p/preview.md): 42 recommend
- [Okular](https://hackerapproved.com/p/okular.md): 12 recommend
- [MuPDF](https://hackerapproved.com/p/mupdf.md): 11 recommend
- [SumatraPDF](https://hackerapproved.com/p/sumatrapdf.md): 11 recommend
- [Foxit Reader](https://hackerapproved.com/p/foxit-reader.md): 6 recommend

## Cite as

Hacker Approved, "pdf.js", https://hackerapproved.com/p/pdf-js/ (counts from 1,795,640 Hacker News comments, November 2025 to November 2026).