Highlight PDF: how it works
To highlight a PDF, open the Highlight PDF tool, add your file, and drag over the text you want to mark — PDFER draws a translucent yellow layer on top and downloads the result. It's done in your browser, and because the highlight is a vector layer the text underneath stays selectable and searchable.
How to use Highlight PDF
- Open the Highlight PDF tool and add your PDF.
- Drag across the text on each page you want to highlight; click × to remove a mark.
- Click Apply & download.
In your browser vs. uploading to a server
Best for marking up documents for review or study without a desktop editor. Unlike flattening or screenshotting, the highlight is a translucent overlay, so the original text remains selectable, copyable, and searchable.
Frequently asked questions
Does highlighting make the text unselectable?
- No. The highlight is drawn as a semi-transparent layer over the page, so the underlying text stays selectable and searchable.
Can I highlight on multiple pages?
- Yes. Page through the document and drag highlights on any page; they're all applied in one download.
Are my files uploaded to a server?
- No. PDFER runs entirely in your browser using WebAssembly and JavaScript. Your files are read into memory on your device, processed locally, and never sent to PDFER or any third party. Closing the tab or leaving the tool erases them from memory.
Is it free, and is there a file-size limit?
- Yes, it is free with no account, no watermarks, and no daily caps. Because processing happens on your own device, the only practical size limit is your device's available memory rather than a server upload quota.
PDFER is a privacy-first PDF toolkit built by Kiril Urbonas. Every tool runs entirely in your browser — see our security model and privacy policy.