About PDF to PNG

One PNG per page, numbered and zero-padded so an alphabetical file listing keeps the document in order — invoice-page-01.png through invoice-page-12.png for a twelve-page invoice. Resolution is yours to choose between 72 and 600 DPI, and the pixel dimensions each page actually came out at are printed next to the file so you can check before downloading.

By default the page is drawn on white, matching what a PDF reader shows. Turning on the transparent-background option skips that fill and writes an alpha channel instead, which is useful when the PDF holds a logo or a diagram you want to place over something else.

The converter is built on pdf.js, Mozilla's PDF engine — the one Firefox uses for its built-in viewer. Three things happen to every file:

1. Parse. A web worker reads the document structure, fonts and embedded images off the main thread, so a large file does not freeze the page while it loads.
2. Rasterise. Each requested page is drawn onto a canvas sized to your chosen DPI — 150 DPI scales the page by 150/72, since a PDF measures itself in 72-unit points. Fonts the document did not embed come from the standard font set, and CJK text uses the CMap tables shipped with the renderer, so Japanese or Chinese documents do not come out blank.
3. Encode. The canvas is encoded to PNG by the browser and handed back as a download, a clipboard image, or an entry in a ZIP archive assembled in memory.

The limits — 20 documents per batch, 200 MB per file, 500 pages per file — exist because all of this runs on your CPU and in your tab's memory. They are generous for real documents and low enough that a mistyped page range cannot lock up the browser.

Nothing leaves the tab. Parsing, rasterising and encoding all happen on your device; no document, filename or page image is transmitted, logged or stored by PDF to PNG. There is no account to create and no server-side history of what you converted, because there is no server-side anything.

With no round-trip involved, the tool also keeps working after you disconnect from the network — the browser caches the renderer after its first use. Removing a file from the queue releases its in-memory copies straight away and closing the tab releases the rest; nothing is written to disk unless you press a download button.

This covers what PDF to PNG itself does. It says nothing about the rest of your system — a browser extension with page access, a corporate proxy or the device itself are outside what any web page can promise you.