Nobody in grad school should pay for budgeting software. Full stop. On a PhD stipend, the budget app should be free, because paying to manage money you barely have is absurd, and the good news is that the free options are genuinely good. Here is what is worth comparing.
EveryDollar's free tier is the grad school budget planner app I suggest to most people first. Planning, expense categories, no charge. The learning curve is close to zero. If you have never budgeted before, start here and see if the habit sticks. A month will tell you.
Goodbudget's free tier runs the envelope system: divide your money into digital envelopes, spend until one is empty. It is simple to the point of being stubborn, which is exactly why it works on fixed incomes. There is no room for creative accounting inside an envelope. The envelope does not negotiate.
Rocket Money's free tier watches for subscriptions and recurring charges, which makes it a handy grad student expense tracker app even if you never pay a cent. One forgotten subscription found is a meaningful percentage of a monthly food budget. Do that math once and the feature sells itself.
The manual option deserves respect. A spreadsheet costs nothing, never syncs wrong, and forces you to look at every number. Plenty of grad students budget this way for the entire PhD and do fine. There is no shame in the spreadsheet. The spreadsheet is honest.
The catch with every free tier is the same: limited bank sync, limited history, the occasional nudge toward paid. Decide in advance which limits you can live with, and do not let the upsell guilt you. And remember the deeper truth: no app fixes the underlying math. If the stipend does not cover the city, that is not a budgeting problem. The cost-of-living-adjusted offer reports at phdstipend.fyi show which programs actually pay enough to live on. Start with the income. Then pick your free app.