I guess I'm really old school but I just have a spreadsheet for my budgeting, with formulas and charts I've written and maintained over the last 25 years. It's gone from old Microsoft formats (xls/xlsx) to ODS, to Gnumeric, back to ODS, and now I use Apple's Numbers since I have a Mac and an iPhone, and iCloud web works on pretty much any device with a browser I might have in front of me. If I do ever feel like ditching my Mac and going back to an open source OS, I can just export it to ODS again and all my formulas and tools transfer over (I don't use anything proprietary from Numbers, though color fills don't always match right up).
I am salaried with weekly payout, and so I have a weekly chart for where my money goes on payday (bills/loans/cards/savings), an amortization schedule for each account that allows me to see how extra payments will affect the payoff and interest, and a brainstorming sheet for planning future large purchases (cars, maybe a bigger house one day). I can do pretty much anything with this that I could with Firefly III or a paid solution, but (for me at least) this is less hassle and my data stays between me and Apple's iCloud server; I trust them enough with that basic data to not bother with maintaining and securing a VPS just to balance my budget.
I am salaried with weekly payout, and so I have a weekly chart for where my money goes on payday (bills/loans/cards/savings), an amortization schedule for each account that allows me to see how extra payments will affect the payoff and interest, and a brainstorming sheet for planning future large purchases (cars, maybe a bigger house one day). I can do pretty much anything with this that I could with Firefly III or a paid solution, but (for me at least) this is less hassle and my data stays between me and Apple's iCloud server; I trust them enough with that basic data to not bother with maintaining and securing a VPS just to balance my budget.