income/expense plan. I think this is really what you're talking about. I have a google sheet that has a sheet with the budget and another sheet with expected income througout the year. I have a sheet for tax forecasting as well. I use all this to determine just how much income and expenses we'll have across the entire year and then I know how much is leftover to put into retirement.

But to answer your question, google sheets.

We really only have a small handful of budgets that actually are variable enough and discretionary enough to need to be budgeted. Everything else is automated bills and stuff. So rather than use some paid service, I just made a google form where we input expenses as we buy stuff and use a sheet in google sheets to track if we're over budget for that month.