Bank-Integrated Platform for Card Switching and Transaction Linking
When people get a new bank card, they have to update it on every site they pay with, one by one. People sometimes forget one or more sites, or skip it altogether, so the bank's card stops getting used. This platform lets them update their card across all those sites from inside their banking app. I worked as a core engineer on the team that built it.
Understanding the problem
Updating a new card everywhere takes real effort. You log in to each site, find the payment settings, and type in the card by hand. People often forget some sites, or skip them altogether. When that happens, the bank's card doesn't get used for recurring payments, and the bank loses out.
Solution overview
The bank adds a ready-made SDK to its app, so people never leave the bank's app
A person picks the sites to update and logs in once through the SDK
The backend then logs in to each site and updates the card in the background
With the user's permission, it also pulls recent transactions for the bank
The bank uses that data for spending summaries, subscriptions, and budgeting
How we engineered
Built and maintained the automation for each merchant: checking sessions, refreshing them, seeing if a card is already the default, and adding or replacing it
Handled full logins too, creating a session from credentials and verifying the OTP
Studied each site's CAPTCHA protection and connected solver tools where possible
Built the logic to save and reuse sessions, so a failed task could be retried days later
Was first to handle failed tasks on call: read logs, fixed urgent bugs, and retried with updated sessions
Kept merchant libraries up to date as sites changed, added tests, and set up GitHub Workflows
The Impact & Results
The bank's card stays the default, so recurring payments don't drop off
Updating a card everywhere takes a few taps, not a login on every site
Banks get detailed transaction data for summaries and budgeting tools
Saved sessions and CAPTCHA handling keep tasks working on hard sites
Card numbers stay tokenized, and login sessions are kept in a separate, secure space
Tools used & implementation layers
- TypeScript
- Python
- Web SDK
- Reverse Engineering Services
- Merchant Integrations
- GitHub Workflows
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