F-Droid

Actual Budget went open-source a while back! It’s self-hostable and fantastic alternative to YNAB. YNAB’s budgeting philosophy has garnered a bit of a cult following, and I highly recommend their budget method (which is a mix of envelope and zero-based budgeting, iirc). Actual Budget is built to mimic YNAB, so it’s perfect. There’s a community of contributors adding features. There’s an option to encrypt your budget, so that whatever server you host it on cannot see it. I highly recommend this app.

Another up-and-coming alternative to YNAB is Budget with Buckets, which is not free. But does have an unlimited free trial lol, and a good privacy policy. It’s still developing though, but it is good!