🖍️ Highlight & Underline PDF

Highlight fills a rectangle with a translucent color behind the text — like a real highlighter marker. Underline draws a colored line at the bottom edge of the area you drag. Strikethrough draws a line through the vertical middle. All three use the same color picker and share the appearance controls.

In Auto-fit mode, clicking anywhere on a line of text automatically creates a highlight that fits that text line exactly — no dragging needed. This is the fastest way to highlight words, sentences, or whole paragraphs. Switch to Free draw when you need a custom-sized rectangle.

They're drawn as real PDF rectangles with transparency (and multiply blend for highlights), not as clickable annotation widgets. This means they can't be removed in Adobe Acrobat the way native highlighter comments can — but they also never break or display incorrectly in different readers. If you want clean, permanent markup, this is the better format.

Yes — while you're still in the tool. Click any annotation on the page (or in the sidebar list) to select it, then either press the red × button or use the Clear All button. Note: once you download the PDF, the highlights become permanent — re-upload and re-apply if you want to change them.

Six classic highlighter colors — yellow, green, pink, blue, orange, and purple — plus a full custom color picker with hex input if you need a brand-specific shade.

No. Everything — preview rendering, text detection, and embedding — happens in your browser using pdf.js and pdf-lib. Your file never leaves your device.