YNAB expects you to put your money into budgets based on whatever money comes in. But that's not how Firefly III works. Firefly III works the other way around. At the start of the month, you decide what you want to spend. If everything is OK, your budget should at least match what you earn. So that's easy. But if everything is better than OK, you budget less than you make, and you save the rest. You can use the rest of the money to fill piggy banks or donate to me (kidding ;)).
But that's really not so different from Actual Budget approach!
At the start of the month, you decide what you want to spend. If everything is OK, your budget should at least match what you earn. So that's easy.
Same. Every dollar coming in has a purpose.
But if everything is better than OK, you budget less than you make, and you save the rest.
Same. The only difference is that you explicitly decide (or change your budget after you realize you have extra -- this is allowed and encouraged) that the purpose for the "remaining dollars" is "savings". Seems the same to me.