Annotating a PDF — highlighting key passages, adding margin notes, drawing attention to specific areas — is essential for studying, reviewing contracts, or collaborating on documents. Here is how to do it for free without any desktop software.
Go to pdfeditor.onl/pdf-studio. The editor includes text, drawing, and annotation tools. Upload your PDF to get started.
Select the Highlight tool and drag across text to mark it. Choose yellow for standard highlights or use other colors to categorize annotations (e.g., green = confirmed, red = needs review).
Tip: On mobile and tablet, tap and hold to start a text selection, then release to apply the highlight. Touch-based highlighting works in the same way as mouse-based.
Use the Add Text tool to type comments directly on the page. Position them in the margins next to the relevant content. Use a small font size (8–10pt) and a contrasting color (e.g., red) for margin notes.
The Pen/Draw tool lets you draw freehand annotations — circles, arrows, underlines, or boxes around important content. Useful for marking diagrams or pointing to specific values in a table.
Click Download PDF. All annotations are permanently embedded in the file and visible in any PDF reader.
Once downloaded with annotations embedded, they are part of the PDF. To remove them later, you would need to re-upload and use the erase or flatten tools.
Yes. All annotations — highlights, text, drawings — are embedded in the PDF and will print exactly as they appear on screen.
Unlock the PDF first using pdfeditor.onl/unlock-pdf, then open it in PDF Studio for annotation.