PDF Annotator
Add highlights, text notes, and freehand drawings to any PDF. Mark up contracts, papers, and reports right in your browser — no upload to any server, no signup. Download the annotated PDF with annotations baked in.
Drop PDF here or click to upload
Highlight, note, and draw · Annotations baked into final PDF
PDF Annotator runs 100% in your browser
Your files are never uploaded to any server. All processing happens locally on your device using modern browser technology. Private, fast, and free.
0
Uploads
0
Stored
How to Annotate a PDF Online
Open the PDF Annotator
Navigate to the tool. No signup, no upload to a server.
Upload your PDF
Drop the PDF you want to mark up. Each page renders directly in your browser for annotation.
Pick an annotation tool
Choose Highlight for yellow marker on text, Text Note for sticky-note style comments, or Draw for freehand pen marks.
Click, drag, and annotate
Click and drag on the page to add highlights or text boxes. With the draw tool, hold and move your mouse like a pen. Navigate between pages with the arrows.
Download the annotated PDF
Hit Save to PDF — all annotations are baked into the file. Download instantly.
Pro Tips
- •Highlights are translucent so the underlying text remains readable — ideal for review and note-taking on PDFs.
- •Text notes are placed where you click — keep them short for clarity. Long notes work better as a separate document.
- •Hold and drag the draw tool slowly for precise lines — great for circling specific words or drawing arrows to comments.
- •Use ‘Undo’ to step back through your annotations if you make a mistake.
- •Annotations are baked into the PDF on download — they’re permanent once you save. Keep an original copy if you want to re-edit later.
Who needs PDF Annotator?
Students
Academic work and assignments
Professionals
Business and office tasks
Creatives
Design and content creation
Everyone
Personal everyday tasks
When to Use PDF Annotator
Contract review
Highlight key clauses and add notes for negotiation points before sending back to counsel — without uploading sensitive contracts to third-party servers.
Academic paper annotation
Highlight key findings, add notes about citations, draw arrows to specific data points — essential for literature reviews and thesis work.
Document feedback
Mark up drafts with highlights and comments before sending back to the author. Faster than typing a separate review document.
Tax and financial review
Annotate tax returns, financial statements, or accounting documents privately. Highlight items that need follow-up without exposing your financials online.
Frequently Asked Questions
Is my PDF uploaded?
No. PDF rendering and annotation happens entirely in your browser using pdfjs and pdf-lib. Your document never leaves your device.
Can I edit annotations after saving?
Annotations are baked into the downloaded PDF — they become part of the document content. To re-edit, work with the original PDF and re-annotate. Future versions of the tool may support editable annotation layers.
Will my annotations show in other PDF viewers?
Yes. Since the annotations are drawn directly onto the page content, every PDF viewer (Adobe Reader, Preview, Chrome, mobile apps) displays them identically.
Can I annotate scanned PDFs?
Yes — the tool works on any PDF regardless of whether it’s text-based or scanned. Annotations are drawn over the page image.
How many annotations can I add?
No hard limit. Most users add 5-20 per document, which works well. Very large numbers (hundreds) may slow your browser.
PDF Annotator vs Alternatives
Annotating PDFs is a daily need for students, lawyers, reviewers, and researchers.
Adobe Acrobat
Industry standard
Key difference: Powerful with editable annotation layers, but requires a paid subscription. Overkill for simple highlighting and notes.
Preview (macOS)
Built-in Mac tool
Key difference: Free and good for Mac users, but Windows users have no equivalent built-in option.
Online PDF services
Smallpdf, iLovePDF, etc.
Key difference: Convenient but require uploading your file to their servers — a real privacy concern for contracts, legal docs, or medical records.
Browser-only processing, no upload, no signup, three core annotation tools that cover 90% of use cases, instant PDF download.
Good to know
- All processing happens in your browser. Very large files may be slower on mobile devices or older computers.
- Results depend on the quality and format of your input. For best results, use high-quality source files.
- Once you close the browser tab, all data is gone. Make sure to download your results before closing.
Key Features
100% Free
No hidden fees, no premium tiers, no limits on how much you use it. Free today, free tomorrow, free forever.
Complete Privacy
Your files never leave your device. Everything is processed locally in your browser — we physically cannot access your data.
No Registration
Start using the tool immediately. No account, no email, no personal information required. Just open and use.
Works Everywhere
Compatible with Chrome, Firefox, Safari, and Edge on desktop and mobile. Works offline once the page has loaded.
Full Step-by-Step Guide
Detailed walkthrough with pro tips and best practices for getting the best results every time.
Read guideFrequently Asked Questions
Every common question answered — file limits, privacy, supported formats, compatibility, and more.
View FAQCompare Alternatives
See how PDF Annotator stacks up against Adobe, Smallpdf, and other paid and free alternatives.
Compare now