UPI Payment Gateway Integration

​Job Title
​Expo React Native Developer – UPI Payment Gateway Integration (Razorpay / PhonePe / Cashfree)
​Project Overview
​We are looking for an experienced React Native (Expo) developer to integrate a seamless UPI payment gateway into our mobile application. The ideal freelancer must have hands-on experience setting up payment flows, deep-linking with native UPI apps (Google Pay, PhonePe, Paytm, BHIM), handling webhooks, and testing in both sandbox and production environments.
​Scope of Work & Steps Involved
​Step 1: Environment & Architecture Setup
​Configure Expo Development Build / Config Plugins (EAS) if native dependencies or custom schemes are required.
​Set up environment variables (.env) for test and production API credentials safely.
​Step 2: Backend & Order Creation Logic
​Create a secure backend endpoint (Node.js/Express or existing API) to trigger the gateway’s "Create Order / Payment Intent" API.
​Generate order tokens and pass transaction payloads securely to the app frontend.
​Step 3: Frontend UPI Flow & UI Integration
​Build the checkout UI in the Expo app allowing users to select UPI as the payment method.
​Support UPI Intent (directly launching Google Pay, PhonePe, Paytm, etc.) or UPI Collect (VPA address).
​Handle deep-linking redirects back to the Expo app post-payment.
​Step 4: Webhook & Server-Side Verification
​Set up a server-side Webhook listener to handle payment status updates (SUCCESS, FAILED, PENDING).
​Implement signature verification to secure webhook payloads against tampering.
​Step 5: Testing & Go-Live
​Perform end-to-end sandbox testing using test UPI handles/credentials.
​Verify failure, timeout, and cancellation states in the app UI.
​Transition to production API keys and conduct live transaction verification.
​Payment Gateway Setup Instructions (Step-by-Step)
​Merchant Onboarding:
​Register and complete KYC on the chosen Payment Gateway portal (e.g., Razorpay, PhonePe, Cashfree, or PayU).
​API Key Generation:
​Generate Key ID and Key Secret from the Merchant Dashboard for Sandbox (Test) and Production (Live) environments.
​SDK / WebView Configuration in Expo:
​Add the relevant Expo config plugins or native SDK modules (using EAS Build) or set up a secure WebView flow.
​Configure deep-linking scheme in app.json (e.g., scheme: "myapp") to enable smooth app redirection after payment.
​Order Creation & Verification Setup:
​Pass transaction parameters: amount, currency (INR), order_id, and callback URLs.
​Verify payments server-side before updating database records.
​Deliverables
​Fully functional UPI payment flow inside the Expo app (iOS & Android).
​Backend integration code for order creation and webhook listener.
​Clear documentation explaining how to update live API keys and test payments.
​Required Skills
​React Native / Expo (EAS Build)
​Node.js / Backend API development
​Payment Gateway Integration (Razorpay, PhonePe, Cashfree, or PayU)
​Deep Linking & Webhook Handler configuration