Unified Payment Gateway
Supercharge your checkout. Accept every payment that matters in Nepal — with a single integration.
The CellPay Unified Payment Gateway (UPG) is a single API layer that allows merchants to accept payments from all major payment instruments in Nepal — wallets, mobile banking, internet banking, cards, QR, and more — without building separate integrations for each provider.
Why UPG?
| Without UPG | With UPG |
|---|---|
| Integrate with eSewa, Khalti, Fonepay, ConnectIPS separately | One integration. All instruments. |
| Maintain multiple API keys and credentials | One secret key from the CellPay portal |
| Build custom redirect and callback logic per provider | One redirect URL. One callback standard. |
| Handle 8+ error format variations | One unified error schema |
What You Get
- ✅ Two APIs only — Instrument Fetch + Checkout. That's it.
- ✅ All major Nepali payment instruments in a single drop-in solution
- ✅ HMAC-SHA256 signature-based security — tamper-proof transactions
- ✅ Merchant portal — configure redirect URLs, retrieve your secret key, monitor transactions
- ✅ Sandbox environment — test every instrument without real money
High-Level Architecture
Your Website
│
├─── GET /payment-instruments ──► CellPay UPG ──► Returns available instruments
│
└─── POST /checkout ────────────► CellPay UPG ──► Validates signature
│
└─► Routes to Provider
(eSewa / Khalti / Fonepay / etc.)
│
Customer pays
│
CellPay confirms payment
│
◄── Redirects to your redirectUrl
Who Is This For?
This documentation is intended for:
- Backend developers integrating the UPG APIs
- Frontend developers rendering the payment instrument UI
- Technical leads evaluating the integration model
tip
For Non-Technical Stakeholders If you are a merchant owner evaluating CellPay UPG, start with the How It Works page.