I built a thing to delete dead git branches

One of my repos had 485 branches. Maybe 50 were alive. The rest were merged-and-forgotten features, dead spikes, and a few hundred sync-main-to-dev-* branches some automation kept spitting out and never cleaning up.

Deleting them by hand is the kind of chore I'll avoid for months, partly because it's boring and partly because I'm scared of nuking a branch that had work I forgot about. So I made git-tidy.

npx git-tidy-cli

It only ever offers to delete stuff that's safe: branches already merged into your default branch (the commits live on in main, so you lose nothing), and never main/develop/staging/production or whatever you're sitting on. And it's dry-run by default, so a first run just prints a list.

It also has a --json mode, which means I can point an agent at it: "tidy the merged branches older than 90 days on origin" and it shows me the list before touching anything.

The first time I used it for real I nearly made a mess. I wanted to clear out old sync branches, so I ran --pattern 'sync-*' --age 7. The dry-run came back with about half the repo. Took me a second to realise the filters were OR'd: it read that as "sync branches, or anything older than a week." Not what I meant. So I added a --match all flag for when you want every condition to hold:

git-tidy --match all --pattern 'sync-*' --age 7 --scope remote

Then I pointed it at three of my repos. I read each dry-run, hit execute, and watched 449 branches disappear — 884 down to 435. Didn't lose anything that wasn't already in main. The funny part was how little of that was real work. Almost all of it was one sync bot that had been quietly littering for a year because nobody wired up the cleanup.

That's the whole tool. It's on npm and GitHub. Go run it on your worst repo and see what falls out.