Highlight Text and Comment on a PDF
Highlight text and add sticky-note comments directly on a page.
Select a PDF to mark up
Click to choose, or drop a file here
You can also paste (Ctrl+V / Cmd+V)
Most tools run entirely on your device
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About highlighting a PDF
Marking up a passage or leaving a note on a specific spot is one of the most common things people want to do to a PDF short of editing the actual text — reviewing a contract, marking a section to revisit, or flagging something for a colleague. This tool lets you draw highlight boxes over any area of a page and drop sticky-note comments at specific points.
Each highlight and comment you place is recorded as a position on the page — as a percentage of the page's width and height, so it stays correctly placed regardless of zoom — and drawn directly onto the PDF with pdf-lib once you apply: highlights as semi-transparent colored rectangles, comments as small numbered markers with the note text alongside. Everything runs in your browser.
Supported files
Accepts a PDF. Produces the same PDF with your highlights and comments drawn onto the pages.
Is my file uploaded?
No. Highlights and comments are drawn entirely in your browser with pdf-lib — nothing is uploaded.
How to Highlight PDF
- 1
Open the tool
Open the Highlight PDF tool and drop your file onto the page, or click to browse for it. Everything runs in your browser — the file is never uploaded.
- 2
Highlight and comment
Drag over text to highlight it, or drop a sticky-note comment anywhere on the page.
- 3
Apply and download
Click Apply and download the annotated PDF.
Highlight PDF — frequently asked questions
Is this the same as Redact PDF?+
No — Redact permanently destroys what's underneath by flattening the page to an image. Highlighting draws a translucent color over the text, which stays fully intact, selectable, and searchable underneath.
Are the highlights and comments real, editable PDF annotations?+
No — they're drawn directly onto the page as part of its permanent content, the same way the other stamping tools here work. They won't show up in another app's "comments" panel, and can't be toggled off later.
Can I mix multiple colors on one page?+
Yes — pick a color before drawing each highlight or dropping each comment; every mark keeps the color it was given.
Is there a free way to highlight text and comment on a PDF?+
Yes — this tool. It works entirely in your browser, free and with nothing uploaded.
Do you upload my files to a server?+
No — every tool here processes your files entirely on your device, and nothing is uploaded to a server. The only exception is the AI tools, which send the extracted text (not the file) to Claude to do their work.
Is there a file size limit?+
There's no artificial limit we impose, but since processing happens in your browser, very large files (500+ MB or 1,000+ pages) are limited by your device's memory rather than by us.
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