DownloadChecker by patois

See at a glance which files on a download page you already have. DownloadChecker marks every download link: green ✔ = downloaded, yellow ⚠ = incomplete or wrong size, red ✖ = still missing. A small box in the corner counts them and lists what is missing.

It works on any page, with special support for GitHub releases (including a size check against the server and "Source code" archives) and SourceForge. Numbered copies like "file(1).zip" count as the same file.

• Toolbar button to switch the marking on and off
• Choose which file extensions count as downloads
• Light and dark theme, or follow the browser
• English, German, French, Italian and Spanish

Privacy: DownloadChecker reads Firefox's download list and remembers finished downloads locally in Firefox. Nothing is sent anywhere. The only network requests are to GitHub, to check the size of release files.

Limits: an extension cannot look at your disk. Files you deleted or moved still count as present until Firefox notices; you can clear the remembered list in the options. Only downloads made with this Firefox profile are recognised.

DownloadChecker is free. If it helps you, I’d appreciate a donation: https://vereo.ch/software/downloadchecker-firefox