How to use Grayscale PDF
- Select the PDF.
- Choose a resolution (200 DPI is a good default).
- Click “Convert to grayscale”.
How it works
Each page is rendered at the chosen resolution, converted to gray tones and saved as a compressed image page. This guarantees there is no color left anywhere, but text becomes part of the image (not selectable). Use OCR PDF afterwards if you need searchable text.
🔒 Your files never leave your device
bopdf processes your documents locally with JavaScript (pdf-lib and Mozilla pdf.js) inside your browser tab. Your PDF is never uploaded, stored or seen by us — you can even disconnect from the internet after the page loads and the tool keeps working. When you close the tab, everything is gone.
Frequently asked questions
Will the file get smaller?
Often, especially for color scans.
Is the text still selectable?
No, pages become images.
Are my files uploaded to a server?
No. Everything happens in your browser on your own device. Files are never sent over the internet, which makes bopdf suitable for confidential documents.
Is there a file size limit?
There is no fixed limit, but very large files (hundreds of MB) depend on your device memory. On phones, files up to about 100 MB usually work well.