PaperFlow 作者: Md. Mehedi Hasan Rafy

PaperFlow lets you highlight and underline text in PDFs directly inside
Firefox's built-in PDF viewer — no external apps needed.

Features:
- Yellow highlights and red underlines on any PDF text
- Floating toolbar appears on text selection
- Annotations persist across browser sessions
- Works on web PDFs, local files, and embedded PDFs
- Undo with Ctrl+Z
- Export annotations as JSON
- Enable/disable toggle in the popup