Rasterization: what converting to JPG really does
A PDF page is not a picture. It's a program of drawing instructions — text runs with embedded fonts, vector paths, embedded images (this object model is defined in ISO 32000). It has no inherent resolution: a page renders crisply whether you view it at 50% or 500% zoom, because the viewer re-executes the instructions each time. Converting to JPG executes those instructions exactly once, at one fixed resolution, and keeps only the resulting pixels. Text stops being text — it can't be selected, searched, or read by a screen reader afterwards.
That's not a flaw of this tool; it's what "PDF to image" means anywhere. Choose it when you need pictures — a slide, a preview, a page to paste into a chat — not when you need a document.
The engine: PDF.js in your browser
Rendering uses PDF.js, Mozilla's open-source engine — the same code Firefox uses for its built-in PDF viewer. It runs entirely in your tab: the engine parses and decodes the document in a background worker thread, then draws each page onto a canvas. The engine loads only when you convert; visiting this page costs nothing extra.
Resolution and quality, concretely
Pages render at 2× their nominal PDF size: an A4 page (595×842 points) becomes roughly 1190×1684 pixels. That's crisp on screens and in documents — it is not print-shop resolution. Each rendered page is then encoded as JPEG at 90% quality, a deliberate middle ground: visually clean for text and graphics, far smaller than lossless output would be. If you need pixel-perfect output instead, switch the output format to lossless PNG — or WebP where your browser supports encoding it; JPG stays the default as the best size-for-quality choice for typical pages.
No upload, verifiable
The PDF is read locally via the File API, rendered inside your tab, and each page image is offered as a direct download. No server receives the document. Verify it yourself: open your browser's network inspector while converting and you'll see no upload, or switch your connection off entirely — after the page has loaded once, conversion still works offline.
The honest limitations
This is a one-way street: there's no faithful way back from pixels to a real PDF, and embedding the images in a PDF wrapper afterwards doesn't restore text or vectors. Password-protected PDFs are rejected outright — decrypt the file first. Very large or graphics-heavy documents are limited by your device's memory and patience, since every page is rendered at full size in memory before it's handed off for encoding. And if what you actually need is selectable text or a smaller extract rather than pictures, the split tool on this site is the right choice, not conversion.