ABOUT THE PROJECT

Integrating POS systems, payment terminals, and business logic into one consistent flow.

This project is a focused POS documentation site for developers working with terminal and in-app payment flows. The goal is to make the app, the integration layer, and the supporting docs feel consistent.

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Built for payment flows

The project focuses on the user journey around on-device and off-device payment handling.

Clear documentation structure

The docs are organized so you can move from intro to architecture, UI components, and database notes.

Practical Android setup

The stack is centered on Android Studio, Gradle, Room, and integration steps that are easy to follow.

WHAT WE BUILT

This project was developed during a LIA (Learning in Work) experience, where we designed and implemented POS system from scratch, covering architecture, payment flows, and core system behavior.

We started with on-device payments using a terminal and later expanded into off-device flows to support more flexible business scenarios. The payment layer is built on a repository abstraction over an event-driven SDK, providing clean suspending operations, predictable transaction handling, and stable UI integration.

The system supports advanced flows such as split payments and refunds

Beyond payments, we integrated barcode scanning via the terminal SDK and external printing via Epson ePOS. On-device flows use terminal capabilities combined with our own logic, while off-device flows required additional custom implementations.

We implemented our own receipt system instead of relying on terminal-generated receipts. It builds receipts from real transaction data, including products, variants, discounts, VAT, and payment details, and supports bank slips, barcodes, branding, and refund receipts.

Product and order management is powered by a structured Room database, enabling reliable handling of variants, pricing logic, and full order lifecycle tracking.