I'm reluctant to because I've had zero time to dedicate to it for a couple of years and there's a laundry list of improvements I have been intending to make.
This is great. Perfect for when you need to find that Slip Jig you can't remember the name of, or when you quickly need a list of alternate titles for An Phis Fliuch.
But, with that caveat, it's https://www.folktunefinder.com
It's a mix of clojure and java. And there's a half written rust search backend waiting for a rainy day...