When this tool is useful
Review comments, classroom markup, and visible callouts where the original page text does not need editing.
How local processing works
The browser reads each JSON mark's page and normalized bounds, draws a fixed-color highlight or text box directly onto that page, then writes a new PDF.
How to use it
- Prepare Annotate a PDF: Work from a copy and confirm page number, highlight or text type, normalized bounds, basic-Latin note text, and recipient reader. Keep the source unchanged.
- Apply Annotate a PDF: Process locally in the browser. The browser reads each JSON mark's page and normalized bounds, draws a fixed-color highlight or text box directly onto that page, then writes a new PDF.
- Download and verify: Save under a new name. Reopen in two common readers, inspect every marked page at 100%, and confirm each fixed visible highlight or note box appears in the intended bounds.
Important limitations
These are visible page drawings, not editable PDF annotation objects; colors are fixed, basic-Latin text only is supported, and existing PDF text is not rewritten.
Verify the downloaded result
Reopen in two common readers, inspect every marked page at 100%, and confirm each fixed visible highlight or note box appears in the intended bounds.
Private by design
Your files stay in this browser. The tool does not upload the source or output to our servers.
Questions and answers
When should I use Annotate a PDF?
Review comments, classroom markup, and visible callouts where the original page text does not need editing.
What does Annotate a PDF change?
The browser reads each JSON mark's page and normalized bounds, draws a fixed-color highlight or text box directly onto that page, then writes a new PDF.
Which limits and settings matter?
page number, highlight or text type, normalized bounds, basic-Latin note text, and recipient reader. These are visible page drawings, not editable PDF annotation objects; colors are fixed, basic-Latin text only is supported, and existing PDF text is not rewritten.
How do I verify the result?
Reopen in two common readers, inspect every marked page at 100%, and confirm each fixed visible highlight or note box appears in the intended bounds.