Step-by-Step Guide
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Step 1
Open the Edit PDF tool
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Step 2
Upload your PDF
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Step 3
Select an annotation tool: Highlight, Text Box, Draw, or Sticky Note
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Step 4
Click on the PDF to place your annotation
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Step 5
Save your edits and download the annotated PDF
Key Benefits
Multiple Tools
Highlight, draw, add text boxes, sticky notes, and shapes.
Private
PDF and annotations stay in your browser.
Any PDF
Works on all standard PDF files.
Free
Full editor with no feature locks.
Common Use Cases
▶ Use Case 1
Review and mark up contracts or agreements before signing
▶ Use Case 2
Add comments and notes to academic papers
▶ Use Case 3
Highlight key sections of reports to share with colleagues
▶ Use Case 4
Fill in text fields on non-interactive PDF forms
Expert Tips
Use the highlight tool with different colours to categorise annotations
Text boxes are perfect for filling in PDF forms that don't have interactive fields
Combine with the Sign PDF tool for a fully reviewed and signed document
Save your work frequently — annotations are saved in the downloaded PDF
Frequently Asked Questions
Can I edit the existing text in a PDF? ▼
Browser-based editing replaces or covers existing content with new layers. True text editing (changing a word in the original text) requires server-side PDF processing.
Will my annotations be visible to others? ▼
Yes — all annotations are flattened into the PDF on download, so they appear as permanent visible changes.
Can I undo annotations? ▼
While editing, use Ctrl+Z (or Cmd+Z on Mac) to undo recent actions before downloading.
How the PDF Editor Works Technically
PDF.js renders each page onto an HTML canvas. An annotation layer sits on top for interactive editing. When you save, pdf-lib flattens all annotations permanently into the PDF output. Highlight adds a semi-transparent colour rectangle. Text box places editable text (ideal for filling non-interactive form fields). Freehand drawing captures mouse or stylus strokes. Sticky note adds a collapsible comment. All annotations appear in any PDF viewer after download.
For a complete review workflow: highlight key clauses, add text box comments, circle issues with freehand drawing, then sign on the final page with the Sign PDF tool. Download, email back. No software, no account, no cost — done in minutes entirely in your browser.
Ready to try it yourself?
100% free, browser-based — no upload, no sign-up, no watermark. Works instantly on any device.
Edit PDF Free →