Highlight and Annotate a PDF
Highlight words and add notes to your PDF.
🔒 Your file is processed inside your browser. It is never uploaded or saved.
What is PDF Annotator?
Type the words you want to find and the tool highlights every match across the document in a colour you pick. You can also add a short note on a page. It is a fast way to mark key terms in a contract, article or study document.
How to highlight and annotate a PDF
- Upload the PDF.
- Type words to highlight, separated by commas, and choose the colour.
- Optionally type a note and the page it belongs on.
- Press Start; the result shows how many highlights were added.
When PDF Annotator is useful
Reviewing contracts
Highlight names, dates and amounts.
Studying
Mark key terms in lecture notes.
Proofreading
Flag words to check.
Tips for better results
Search works on text-based PDFs; scanned pages have no text to match. Matching ignores upper and lower case. Notes are plain English text placed near the top of the page.
Good to know before you start
Highlighting uses text search: for every word you list, the tool finds each occurrence on every page and draws a semi-transparent rectangle over it, so the underlying words stay readable. Matching is not case sensitive and also finds the word inside longer words, so "fee" would highlight part of "feet". Use specific terms for better results. The summary below the button tells you how many highlights were added. A single note can be written on the page you choose, in red, near the top margin. The tool does not create editable comment bubbles; everything is drawn into the page.
Why use PDFToolkit
When you highlight and annotate a PDF with PDFToolkit, the work stays on your own device. Your contracts, ID scans and invoices are processed in the browser and are never sent to a server.
- Private: no upload, nothing saved.
- Free: no sign-up, no daily limit and no watermark.
- Fast: no waiting for files to travel over the internet.
- Everywhere: Windows, Mac, Linux, Android and iPhone.
Frequently asked questions
Can I highlight by dragging with a mouse?
No. You type words to find.
Does it work on scans?
Only on PDFs that contain text.
Can I choose a colour?
Yes: yellow, green, blue or pink.
Is the file uploaded?
No.