How to Annotate and Comment on a PDF Online for Free
Reviewing contracts, research papers, or design PDFs? Learn how to add highlights, sticky notes, drawings, and stamps to any PDF directly in your browser.
Reviewing a contract, marking up a research paper, or giving feedback on a design PDF — annotations make the review process faster and clearer. Modern browser-based tools let you annotate PDFs without Adobe Acrobat or any installed software.
Types of PDF Annotations
- Text highlight: Mark important passages in yellow, blue, or red
- Sticky notes / comments: Add text notes attached to specific locations
- Underline and strikethrough: Standard proofreading marks for text edits
- Freehand drawing: Draw arrows, circles, or free-form shapes
- Text boxes: Add typed text anywhere on the page
- Stamps: Pre-made labels like "Approved", "Rejected", or "Draft"
Annotating for Document Review
When reviewing contracts or reports, a consistent annotation approach helps:
- Yellow highlight = important, needs attention
- Red highlight = issue or disagreement
- Sticky note = question or comment
- Strikethrough = text to be deleted
Saving Your Annotations
Annotations can be saved in two ways: embedded in the PDF (others can see them when they open the file) or as a separate layer that can be toggled. Most browser-based tools embed annotations by default, which is what you typically want for sharing.
Sharing Annotated PDFs
Once annotated, download the PDF and share it via email or cloud storage. The recipient can see your annotations in any standard PDF viewer — no special software required. This makes browser-based annotation perfect for team document review workflows.