How do you and your partner keep track of shared money?

Hi! I'm Filipe, and tomorrow I'm launching Mayora here, a shared budget for couples and households. I built it because my partner and I kept ending the month with two different ideas of what we had spent. Before the launch I'd love to hear how you do it today: a spreadsheet, a joint account, an app, or nothing at all? And what makes you give up on a budget?