When you tap a Fintech against a reader, you're watching the tail end of a conversation that started long before your card touched the terminal. The reader's antenna is broadcasting a weak radio field constantly, waiting for a compatible chip to enter range.
The moment your card's chip is powered by that field, it and the terminal exchange a short cryptographic handshake — proving the card is genuine without ever transmitting your actual card number over the air in the clear. This is the same family of standards (ISO 14443) used by contactless bank cards worldwide.
Once the handshake completes, the terminal checks your card's last known balance (cached locally on the terminal for offline resilience, and reconciled with our servers continuously), deducts an estimated fare, and flashes green. The exact fare — based on your boarding and alighting stops — is only finalized when you tap out.
All of this happens in under 300 milliseconds, which is why boarding a bus with Fintech barely breaks your stride.