This is an overlay editor — you're placing elements on top of the PDF, not editing the original content underneath. That's an important distinction. You can add text, cover something with a white box and write over it, place an image, draw a signature. You can't reach into a paragraph that came with the file and change a word mid-sentence. That would require the original Word doc or InDesign file. For filling forms, adding annotations, labelling diagrams, or making a quick correction, the overlay approach handles it fine.

A few things worth knowing before you start

When you place a text box over existing PDF text, the tool tries to match the font the PDF used. PDFs embed font names but not the actual font files, so there's a mapping to the nearest available web font — Helvetica becomes Inter, Times New Roman becomes a serif equivalent, and so on. It's close, not exact. If you need the new text to blend invisibly with the original, set the font and size manually. The find and replace panel (under Extras in the toolbar) searches across all pages, not just the current one — useful on long documents. Undo goes back 50 steps per session and resets when you upload a new file.