Annotate a PDF online
Highlight a passage, underline a figure, strike out a clause or sketch in the margin. windpdf writes standard PDF annotations, and its highlights follow the text even when the text is rotated.
Drop your PDF here to start
to use Annotate (free, no account)
Files stay private: PDFs and images are edited in your browser.
Highlights follow rotated text
Highlight quads are computed per glyph line, so a highlight on rotated text is painted at the same angle, not as a horizontal strip.
Standard annotations
Highlights, underlines, strikeouts, ink and notes are written as real PDF annotation objects: they stay editable and can be flattened into the page later.
Runs in your browser
Your file is processed on your device and only uploaded if you choose to save it to your drive.
A review layer you can still take back
Highlights, ink, shapes and notes are written as standard PDF annotations, so they stay objects until you decide to freeze them.
Highlight, then say why
Highlight quads are computed per glyph line, so the colour sits exactly on the words. A note pin carries the comment next to them.
Real annotation objects
Each markup maps to a standard PDF annotation type, which is why Acrobat, Preview and browsers all display them.
Freeze it when the review ends
Flatten paints the markups into the page and drops the interactive layer, so nobody can move or strip them afterwards.
This is irreversible.
Rotated text gets a rotated highlight
The highlight follows each glyph line at its real angle instead of dropping a horizontal bar across the page.
A full review toolkit
- Highlight, underline and strike out text with per-glyph precision
- Draw freehand with pen or marker, erase strokes
- Drop sticky-note comments on the page
- Rectangle and shape tools for callouts
- Flatten everything into the page when the review is final
Annotations you can still change your mind about
Because annotations are standard PDF objects, they are never baked in until you say so: move a highlight, recolor it, or delete it. When the document leaves your hands for good, the Flatten tool freezes them into the page content.
Done in three steps
Upload your PDF
Drop the file above, it is read locally in your browser, never uploaded to a server.
Use the tool
The editor opens with the right tool selected. Make your changes in a couple of clicks.
Download the result
Save the finished PDF straight to your device. No account, no watermark, no wait.
Frequently asked questions
Yes. The highlight follows each glyph line at its real angle, so rotated text gets a rotated highlight instead of a horizontal bar.
Yes. Annotations stay editable objects until you flatten or export: select one and delete it, or undo with Ctrl+Z.
Yes. They are written as standard PDF annotation types (Highlight, Underline, StrikeOut, Ink, Text), readable by Acrobat, Preview and browsers.