How offline PDF to JPG conversion works
This tool uses Mozilla pdf.js — the same PDF rendering engine that powers Firefox's built-in PDF viewer. pdf.js is an open-source JavaScript library that parses PDF files and renders them to HTML5 canvas elements entirely in the browser. At no point is your PDF file or its contents transmitted over the network.
Here's the pipeline: your PDF is loaded via the FileReader API into an ArrayBuffer in memory → pdf.js parses the PDF structure → each page is rendered to a canvas at 2x resolution for quality → canvas.toBlob() exports the page as JPG/PNG/WebP at your chosen quality level.
Why convert PDF to JPG?
- Share individual pages — extract a specific diagram, chart, or image from a PDF and share it as a JPG.
- Social media — convert PDF slides, flyers, or artwork to JPG for Instagram, Twitter, or Facebook.
- Preview thumbnails — generate JPG previews of PDF pages for your website or app.
- Compatibility — JPG opens on every device, every app, every platform without a PDF reader.
- Privacy — most online PDF to JPG converters upload your entire PDF to a server. This one processes it locally.
The privacy advantage: client-side PDF rendering
Every major PDF to JPG converter uploads your file to a cloud server: Smallpdf, iLovePDF, Adobe, Zamzar, and dozens of smaller sites all work the same way. Your PDF — including any confidential text, financial data, personal information, or proprietary content — is transmitted to and stored on someone else's infrastructure.
PrivateConvert eliminates this entire risk. Mozilla pdf.js runs in your browser's JavaScript sandbox. Your PDF is parsed in memory, rendered to canvas, and exported — all without a single network request for the file data. Open DevTools and watch the Network tab stay empty.
Output formats compared
| Format | Best for | File size | Quality |
|---|---|---|---|
| JPEG | Universal compatibility, photos, web | Medium | Adjustable (85% default) |
| WebP | Modern websites, Google PageSpeed | 25-35% smaller than JPEG | Adjustable |
| PNG | Text-heavy pages, screenshots, archival | Larger | Lossless |
How to select specific pages
- Switch to the "Select pages" tab
- Type page numbers and ranges in the input — e.g.,
1,3,5-8converts pages 1, 3, 5, 6, 7, 8 - Or click individual page thumbnails to toggle them on/off
- Click "Apply" (or press Enter) to confirm your selection
- The "Convert N pages" button updates to show how many pages are selected
Recommended quality settings
- 85–95% — text-heavy PDFs where readability matters. Higher quality preserves sharp text edges.
- 75–85% — general documents, presentations, mixed content. The default 85% is a good balance.
- 50–70% — image-heavy PDFs where file size matters more than pixel-perfect quality.
- PNG — when you need lossless output. Every pixel from the PDF render is preserved exactly.