Annotating a PDF — adding notes, corrections, questions, or drawings on top of the existing content — is something reviewers, students, lawyers, and designers do every day. You do not need Adobe Acrobat to do it well. Here is how to annotate any PDF for free using a browser-based tool.
How to annotate a PDF for free
Filero's Edit PDF tool lets you add text and freehand drawings to any PDF page. Everything runs in your browser — your file is never uploaded to a server, which matters when you are annotating confidential documents.
- Open the Edit PDF tool and upload your PDF.
- To add a text note: select the Text tool, click anywhere on the page, and type your annotation. Drag the text box to reposition it.
- To draw on the page: select the Draw tool, then use your mouse or finger to draw lines, arrows, circles, or freehand marks.
- To add a shape or highlight an area: use the Rectangle or shape tool to draw a box around important content.
- When you have finished annotating, click Save to download the annotated PDF.
All annotations are permanently embedded into the PDF — they are not floating comments that disappear when printed or viewed in a different reader. The annotated version looks the same on every device.
Common annotation use cases
- Document review. Add editorial comments to a draft report, mark up a contract with suggested changes, or flag sections that need more information.
- Academic study. Annotate lecture notes, research papers, or textbooks with questions, summaries, and connections to other material.
- Design feedback. Draw arrows to specific elements on a design mockup, circle a section that needs changing, and add a typed explanation.
- Form completion. Fill in blank fields on a flat PDF form — see our guide on filling out PDF forms for more detail.
- Instruction or tutorial creation. Add step numbers and arrows to a screenshot-based PDF walkthrough.
Annotating on different platforms
On Mac using Preview
Mac's Preview app has solid built-in annotation tools. Open the PDF in Preview, click the markup toolbar button (the pen icon), and you get access to text boxes, shapes, arrows, and freehand drawing. You can also highlight text and add sticky notes. Save with Cmd+S or export to a new file.
On iPhone and iPad
iOS has a built-in markup tool accessible from almost any PDF viewer. In Files or Mail, open the PDF and tap the markup pen icon (top right). You can draw with your finger or Apple Pencil, add text boxes, and annotate in multiple colours. Tap Done to save. The Edit PDF tool also works well in mobile Safari for more complex annotation tasks.
On Android
Android does not have a universal built-in PDF annotator, but the browser-based Edit PDF tool works well in Chrome. Google Drive can also open PDFs — tap the pencil icon to annotate inline and save back to Drive.
Annotation versus editing: what is the difference?
Annotation means adding new content on top of a PDF without changing the underlying document — notes, marks, and overlays that sit above the original text. Editing means modifying the actual content of the PDF — changing what words say, replacing images, or restructuring the document.
Browser-based PDF tools primarily support annotation (overlay-based), which is the right tool for review and markup workflows. True content editing requires either the original source file or a high-end PDF editor. For most review and collaboration workflows, annotation is all you need.
Frequently asked questions
Can multiple people annotate the same PDF?
Not simultaneously in Filero — each person annotates their own copy. To collaborate, one person annotates and saves, then shares the annotated PDF with the next reviewer, who annotates on top. For real-time collaborative annotation, Google Docs (after converting the PDF) or Adobe Acrobat with sharing enabled are better suited.
Will annotations show up when printing?
Yes. Annotations added with the Edit PDF tool are embedded into the PDF permanently, so they print exactly as they appear on screen.
Can I remove or edit an annotation after saving?
Yes — re-open the annotated PDF in the Edit PDF tool, select any text box or drawing element, and delete or move it. Always keep a copy of the original un-annotated PDF if you might need to start fresh.
Ready to try it?
Use Filero's free Edit PDF tool. No account needed, works on any device.
Open Edit PDF