A PDF annotator adds text, highlights, and underlines directly on PDF pages — click to place text, draw to highlight. All processing runs in your browser with no server upload.
Upload PDF
How to Annotate a PDF
This PDF annotator lets you add text, highlight areas, and underline content directly on a visual preview of your PDF page. Annotations are embedded into the PDF using pdf-lib — text annotations are real searchable text, not images.
Step 1: Upload Your PDF
Click or drag a PDF file into the upload area. The tool renders a preview of your PDF using PDF.js. No files are uploaded — everything runs locally in your browser. The preview appears immediately after loading.
Step 2: Choose an Annotation Mode
Three modes are available. Add Text: Type in the text field, then click anywhere on the PDF preview to place it at that exact position. Highlight: Click and drag to draw a semi-transparent rectangle over the desired area. Underline: Click and drag horizontally to draw a line under text. Choose a color and font size before placing annotations.
Step 3: Navigate Pages and Download
Use the Previous / Next buttons to move between pages. Annotations on each page are listed below the canvas with page numbers and types. Use "Undo" to remove the last annotation on the current page. When ready, click "Download Annotated PDF" to generate and save the annotated file.
Annotation Types Explained
Text annotations use pdf-lib's drawText() method — the text is embedded as real PDF text, making it selectable and searchable. Highlights use drawRectangle() with 30% opacity. Underlines use drawLine(). All coordinate math accounts for the canvas-to-PDF coordinate system difference (PDF origin is bottom-left).
FAQ
Is the PDF Annotator free?
Yes, completely free with no signup or account required. Add as many annotations to as many PDFs as you need.
Does my PDF get uploaded to a server?
No. All annotation processing happens in your browser using pdf-lib. Your file never leaves your device.
Does annotation make the added text searchable?
Yes. This tool adds real text to the PDF using pdf-lib's drawText method — it's not an image overlay. The added text is fully searchable and selectable in PDF readers.
Can I change the font color of annotations?
Yes. You can choose from black, red, blue, or green for each annotation. Each annotation can have its own color — you don't have to use the same color for all.
How do I position annotations precisely?
Use the X and Y percentage fields — 0% is the left/top edge, 100% is the right/bottom edge. For example, X=50, Y=50 places text at the center of the page. Y=90 places text near the top (position 90% from the bottom). Try a few values to dial in the exact position.