Turn a color PDF into a clean black-and-white version — easier on printer toner and often smaller — converted entirely on your device.
Color costs money at print time — office printers meter color pages separately, and print shops charge multiples of the black-and-white rate. Some submissions (court bundles, certain journals) explicitly require grayscale. And a colorful document destined for a laser printer often looks worse half-toned by the printer than properly converted in advance. This tool does the conversion once, cleanly, so what you send is exactly what prints.
Each page is redrawn by pdf.js — the renderer built into Firefox — inside a background thread of your browser. The rendered pixels are converted to true luminance grayscale (the same weighting television has used for decades, so blues don't come out too dark and yellows too light), re-encoded as an efficient JPEG, and reassembled into a new PDF with pdf-lib. Colors map to their perceived brightness, which keeps contrast natural and text readable.
The trade-off is the same one the site's PDF compressor states plainly: output pages are images, so text in the converted file is no longer selectable or searchable. For scans that changes nothing; for a digitally created PDF, keep the original for editing and use the grayscale copy for printing and submitting.
The document is opened, rendered, converted, and rebuilt on your own machine — no server sees it, which matters when the file is a contract or a report. Grayscale output is also frequently smaller than the color original, a welcome side effect for emailing. There is no account, no daily limit, and no watermark. Password-protected files need unlocking first; the tool says so clearly.
No. Rendering, grayscale conversion, and reassembly all run in your browser. The file never leaves your device.
No — converted pages are stored as images, so text can't be copied out of the grayscale file. Keep the original for editing; use this copy for printing and submitting.
Often, yes — grayscale images compress better than color ones. It depends on the source: heavily colored scans shrink the most, sparse text documents may not.
Printer drivers half-tone colors on the fly with mixed results, and you can't control it on someone else's machine. Converting first fixes the appearance and works for digital submission too.