Highlighting important passages in a PDF helps when reviewing contracts, studying documents, or marking up reports. Here's how to add color highlights to any PDF in your browser.
Go to pdfeditor.onl/pdf-studio and upload your PDF.
Select the Annotation / Pen tool from the toolbar. Choose a highlight color — yellow, green, blue, or any custom color — and a high opacity. Draw over the text you want to highlight.
Tip: Set pen opacity to around 40–60% and a thick stroke width for a semi-transparent highlight effect that lets the text show through clearly.
Click Download PDF. All highlights are permanently embedded in the document.
Yes. You can switch colors between highlights. Use yellow for important passages, green for action items, and red for concerns.
The highlights are flattened into the PDF page content and cannot be easily removed without specialist software.
Yes — the annotation tool is completely free with no account required.