PDF editing in the browser sounds impossible. The PDF specification stores text as positioned glyphs, not as editable paragraphs. How can you "edit text" when the format was designed to be read-only?
You can't — not really. But you can do everything else: reorder pages, delete pages, insert pages, rotate, add signatures, watermarks, and page numbers. And for many users, that is all they actually need.
This post walks through a browser-based PDF editor built with Vue 3 and pdf-lib.
What you CAN'T do in the browser
Directly modifying existing text inside a PDF requires:
