See the cost of waiting.
Compare paying in full, a set amount, and the minimum - then see the months and the interest each path costs.
Minimum: years to clear · Pay more: monthsCardLab is a private credit card tracker and simulator. Set up a fake-but-realistic card with your real limit, APR, and dates, then test purchases, payments, and payoff plans on a timeline where mistakes cost nothing. The iPhone app also lets you clean up a purchase or payment you logged by mistake.
No bank login · No real card number · Everything stays on your phone
Statement date, due date, grace period - the whole system runs on a 30-day loop. Move your payment across the month and watch interest, grace, and next cycle react. This is the exact math the app runs on your real numbers.
Scenario · $1,450 balance · $3,000 limit · 24.99% APR
Statement day 1 · Payment due day 25
Paid in full, but 2 days late - grace is lost anyway. That costs $25.81 in interest, and next month's purchases accrue from day one.
In the iPhone app, delete a purchase or payment from Timeline with a clear confirmation. Balances update immediately, linked friend repayments are cleaned up with covered purchases, and deleting a repayment reopens what is still owed.
Compare paying in full, a set amount, and the minimum - then see the months and the interest each path costs.
Minimum: years to clear · Pay more: monthsEvery purchase and payment shifts utilization in real time, with an educational Credit Health Meter - never a credit score.
$1,450 / $3,000 → 48% utilization1.5% cashback is real money - until interest eats it. CardLab shows the point where a carried balance costs more than you earn.
1.5% back vs 24.99% APR → you are losingA tutor grounded in your real card, not generic advice. On Apple Intelligence devices it runs entirely on-device; optional CardLab Cloud brings it to every device.
A precise, decimal-based engine runs the same math issuers use, validated by an automated test suite - no hand-waving, no rounded-off guesses.
Everything you need to start.
One-time. Nothing to cancel.
Free to start. $9.99 lifetime Pro. No subscription, no ads, no tracking.