Automatically highlight words or phrases in a PDF

Search for a word or phrase and highlight all matches in a colour of your choice. Useful for emphasising keywords in reports, contracts and articles. Free and local.

Choose your PDF

Drop here or click to choose

Files stay on your device — nothing is uploaded

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Your file is processed in your browser and never uploaded.

How does it work?

1
Choose your PDF
Drag the PDF here.
2
Enter the search text
Type the word or phrase you want to highlight.
3
Choose the colour
Choose a highlight colour.
4
Download
Download the PDF with all highlights.

Frequently asked questions

Does this work on scanned PDFs?

No. Scanned PDFs have no text layer. Use the OCR tool first to recognise text.

Can I highlight multiple words at once?

Enter one search term at a time. Repeat the process for multiple terms — each time existing highlights are preserved.

Are my files uploaded?

No. Everything happens in your own browser. Your file never leaves your device and is not stored anywhere.

Is it free?

Yes, completely free, without watermark or account. The site is paid for by ads.

Why in the browser?

PDFrust runs entirely in your browser using WebAssembly and modern JavaScript libraries such as pdf-lib and PDF.js. Your file is never sent to a server — all processing happens locally on your device. This means your documents remain private by design, regardless of what they contain. There is no account required, no file size limit, and nothing is stored after you close the tab.