Underline PDF Text: Drag to Mark or Find Every Word

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   What's great about our PDF underliner

   • Your PDFs never leave your device. Every line is added right in your browser.
   • Drag to underline any part of a page, or find words and underline every match at once.
   • Five colours and your own, solid or dashed, in any thickness.
   • Move, resize, Undo and delete any line before you save.
   • Underline many PDFs at once, with a ZIP download.
   • Free, no limits, no watermark, and it works offline after your first visit.
2. 01

   Add your PDFs

   Choose PDFs or drag them into the preview. The first PDF opens as a vertical list of large pages, which is the easiest place to underline. Use Add More to add others later.

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   Underline

   • Pick a colour, a thickness, a distance and a style, then drag across the text you want to underline. The line sits just under the text, as far down as the Distance says.
   • Or double click a word, triple click a sentence, or click four times for a whole paragraph.
   • Or type words under Find Words, one per line. Matches are shown in light yellow. Click Underline Matches to mark every one of them.
   • Click a line to select it. Drag it to move it, drag a square to resize it, or press Delete. Undo steps back.
   • Press Ctrl+A (Cmd+A on a Mac) to select every line in your PDFs, then change the colour, thickness, distance or style to change them all.
   • Press Ctrl+C then Ctrl+V (Cmd+C then Cmd+V on a Mac) to copy the selected line and paste it where your pointer is on the page.
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   Underline PDF and download

   Click Underline PDF, then Download. Change anything and the button goes back to Underline PDF, ready for another run. Several PDFs download together as a ZIP.

5. 04

   Loved it?

   • If you're on computer, bookmark this page to your browser.
   • If you're on mobile, add it to your home screen for one-tap access and offline use.
     • Android: Visit this page in Google Chrome > tap three-dot icon (⋮) at top > Install and create shortcut.
     • iPhone and iPad: Visit this page in Safari > tap menu icon in address bar > Share > Add to Home Screen.

How it works

An underline is a thin line drawn just under the text you drag across, over the page. Because the page itself is never redrawn, its text, fonts, images, links and forms stay exactly as they were, and the text above the line stays selectable and searchable.

When you find words, the PDF's text is read page by page, and a line is placed across each match. After the file is made, it is opened again and compared with your original: the page count, page sizes, rotation, text and links must all match what they should. If anything differs, no file is produced for that PDF.

Frequently asked questions

• Is my PDF uploaded anywhere? No. Everything happens in your browser, on your device. Your PDF is never sent to a server.
• How do I underline part of a page? Press on the page, drag across the text you want and let go. The line snaps just under each line of text you dragged across. Click it to select it: it gets a dashed blue outline, and you can move it, drag the squares to resize it, or press Delete.
• Can I underline a word, a sentence or a paragraph with a click? Yes. Double click a word to underline it, triple click to underline its whole sentence, and click four times quickly to underline its whole paragraph. If you click one more time than you meant to, the shorter mark is replaced by the longer one. This works on PDFs that have real text, not scans.
• Can I underline every place a word appears? Yes. Type a word or phrase under Find Words, one per line. Every match in every PDF you added is shown in light yellow right away, so you can see what was found. Click Underline Matches to mark them all, and you can still remove any single one afterwards.
• Will the text stay selectable and searchable? Yes. The line is drawn over the page, so the text under it is never touched or turned into a picture.
• Can the lines be removed later? They become part of the page, so they cannot be switched off like a comment. Keep your original file if you might want the page without them.
• Why does Find Words say nothing was found? The PDF may be a scan, which holds pictures of pages and no text to search. You can still drag lines by hand on a scan.
• Which PDFs are not supported? Password-protected PDFs cannot be processed. Remove the password first with PDF Password Unlock. Digitally signed PDFs can be processed, but rewriting the file invalidates the signature.

What happens to your file

Nothing is uploaded, stored on a server or tracked. Your PDFs stay in your browser's memory until you remove them or close the page. The lines become part of each page, so they cannot be switched off afterwards.

How to get the most out of it

• Use the vertical list of large pages for hand marking. Zoom in with the + button for small print.
• For a long document, use Find Words first, then fix any line by hand.
• Use a dashed line for text you want to double-check, and a solid one for text that is final.
• To highlight or cross out text instead, use Highlight PDF or Strikethrough PDF.
• Keep your original file. Lines cannot be edited once the PDF is saved.