Paytm POS payments app
The Android app on Paytm’s POS devices that merchants use to take UPI, credit and debit card payments, including metro NCMC cards.
- Company
- Paytm
- Role
- Senior Software Engineer
- Year
- 2022–2024
- Stack
- Android, Kotlin, Java, EMV, Spring Boot, Node.js
The problem
A payments app running on dedicated POS hardware has to be secure, certifiable and frugal with battery, while new payment types such as the National Common Mobility Card keep arriving.
What I did
- Implemented ECR (electronic cash register) integration for NCMC transactions.
- Migrated the encryption protocol from 2BDK to 3BDK without a single production issue.
- Reworked the system screensaver to use less power on the device.
- Modularised the app so modules could be released with one fewer approval step.
- Built a GPT-based tool for analysing POS transactions.
Outcome
- Four metro agencies adopted the Paytm payments app for taking payments.
- 10% better device battery life.
- Transaction analysis cut from two days to seconds.
- Named Rising Star at Paytm in 2023.
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