Build an open-source Rust download manager modeled on IDM in ten days

u/Nefzaoui disliked the licence nags in Internet Download Manager and set out to build a free replacement, Mister Download Manager, in Rust for Windows and Linux, with Mac builds still experimental. Claude Code running Opus wrote most of it: the multi-connection download engine, every window, the browser extension, the installers and the project website. The poster set the direction and the look, reviewed the work and tested each release by hand. The project rules that Claude reads forbid any IDM code, artwork or text; behaviour could only be learned from public docs and from using a licensed copy. Several agents ran at once, one issue per agent, each in its own git worktree with its own pull request, and every PR had to include before and after screenshots. Each change had to be proven on the real running app: off-screen windows on Windows, Linux VMs for GNOME, KDE, Xfce and Cinnamon, and real Chrome, Firefox and Waterfox for the extension. Claude also reads incoming crash reports and traces them to the failing line.

Version 0.5, which the poster calls the first complete release, shipped ten days after the project started. It covers the classic layout, browser capture, video through yt-dlp, torrents, debrid services, themes and phone control. Testing against the live app caught a regression the unit tests missed, hours before release. In ten days 28 people opened PRs, filed bugs or joined in. On a local test server the poster measured a 1 GB file in 1.01 s against 5.46 s for IDM 6.42. Running more than three or four building agents at once overloaded the PC.

Commenters argued over whether copying IDM's layout and name style is fair, and one warned about malware risk in future versions, though the code is public under GPL-3.0. Another pointed out that IDM's real value is keeping up with sites that fight download tools, which this project hands off to yt-dlp and debrid services. When two agents touch the main window, the later one merges main and is tested again, and only one agent works on that window at a time.