Using Server-Sent Events for payment confirmation

Polling is not always the best experience for mobile payment confirmation.

While working on a project using Expo, I implemented a payment flow that listens for confirmation through Server-Sent Events.

After payment begins, the app opens an authenticated event stream using the merchant reference. When a successful event arrives, it:

• Stops the pending state
• Updates the payment result
• Closes the connection
• Makes the generated waybill available
• Moves the user into the next part of the workflow

The flow also handles malformed events, connection errors, cleanup when the screen unmounts, and a five-minute timeout when confirmation never arrives.

What I like about this feature is that it connects several parts of the product: payment, status, checkpoints and QR-verifiable waybills.

The result for the user is simple: make the payment and see the trip become ready without manually refreshing the screen.