--- title: Payment Gateway Integration PRD type: prd status: draft created: 2025-11-04 updated: 2025-11-04 --- # Product Requirements Document: Payment Gateway Integration ## Objectives ### Primary Objectives 1. **Enable Real-time Online Payment Processing** - **Goal**: Allow customers to complete purchases instantly without manual invoice processing - **Measure**: Checkout conversion rate and average checkout time - **Target**: 75% conversion rate (up from 55%), average checkout time under 45 seconds - **Timeline**: Launch by Q2 2026, achieve targets within 3 months post-launch - **Why it matters**: Eliminates primary source of cart abandonment (45% currently) and recovers $1.8M in lost annual revenue 2. **Reduce Operational Costs and Manual Work** - **Goal**: Automate payment processing and reconciliation to eliminate manual labor - **Measure**: Hours spent on manual payment processing and reconciliation - **Target**: Reduce from 20 hours/week to 4 hours/week (80% reduction) - **Timeline**: Immediate upon launch - **Why it matters**: Saves $100K annually in labor costs, allows sales/finance teams to focus on high-value work 3. **Improve Customer Satisfaction with Modern Checkout** - **Goal**: Provide seamless, secure checkout experience matching major e-commerce sites - **Measure**: NPS score for checkout experience and payment-related support tickets - **Target**: NPS 50+ (up from 35), reduce payment support tickets by 50% - **Timeline**: Measure within 30 days post-launch - **Why it matters**: Customer satisfaction drives repeat purchases and positive word-of-mouth ### Secondary Objectives 1. Enable subscription and recurring billing capabilities (Phase 2 - deferred 6-12 months) 2. Support international currencies and payment methods (Phase 2 - market dependent) ## Success Criteria ### Launch Criteria (Must-Have) **Functional Completeness** - [ ] Process 100 test transactions with 0% failure rate - [ ] Support card payments (Visa, MC, Amex, Discover) and digital wallets (Apple Pay, Google Pay) - [ ] One-click checkout functional for returning customers with saved payment methods - [ ] Integration with Salesforce CRM and QuickBooks accounting complete - [ ] Email confirmations sent within 30 seconds of successful payment **Quality Standards** - [ ] Payment processing time <3 seconds at 95th percentile - [ ] Checkout page load time <2 seconds - [ ] PCI DSS SAQ-A compliance validation complete - [ ] Security audit passed with zero critical vulnerabilities - [ ] Mobile-responsive checkout tested on iOS and Android **Operational Readiness** - [ ] Stripe integration monitoring and alerting configured - [ ] Webhook processing with retry logic implemented - [ ] Runbooks for common payment issues created - [ ] Support team trained on new checkout flow and troubleshooting - [ ] Customer-facing documentation published ### Success Metrics (Post-Launch) **Adoption Metrics (30 days)** - [ ] **Transaction volume**: 0 → 1,000+ online transactions processed - [ ] **Saved payment adoption**: 60% of customers save payment method on first use **Engagement Metrics (30 days)** - [ ] **Checkout conversion**: 55% → 75% (reduce abandonment 45% → 25%) - [ ] **Average checkout time**: N/A → 45 seconds (90th percentile) **Business Metrics (90 days)** - [ ] **Revenue recovery**: $150K+ in previously abandoned cart revenue - [ ] **Operational cost reduction**: 80% reduction in manual payment processing time - [ ] **Customer satisfaction**: NPS 35 → 50+ for checkout experience **Quality Metrics (30 days)** - [ ] **Payment success rate**: 98%+ of initiated transactions complete successfully - [ ] **System uptime**: 99.9%+ (max 45 minutes downtime per month) - [ ] **Support ticket reduction**: 50% fewer payment-related inquiries ## Functional Requirements ### FR1: Credit/Debit Card Payment Processing **Description**: Process credit and debit card payments securely in real-time with instant confirmation **User Story**: As an online shopper, I want to pay with my credit/debit card directly on the checkout page, so that I can complete my purchase immediately without waiting for invoices **Inputs**: - Card number, expiration date, CVV (via Stripe Elements) - Billing address - Purchase amount and order details - Customer email **Outputs**: - Payment confirmation with transaction ID - Order receipt via email - Updated order status in CRM **Business Rules**: - Accept Visa, Mastercard, American Express, Discover - Require CVV for all transactions (fraud prevention) - Maximum transaction amount: $10,000 (fraud threshold) - Minimum transaction amount: $1.00 **Acceptance Criteria**: - [ ] Given valid card details, when customer submits payment, then transaction processes in <3 seconds - [ ] Given invalid card number, when customer submits, then clear error message displays before submission - [ ] Given successful payment, when transaction completes, then confirmation email sent within 30 seconds - [ ] Given payment failure, when Stripe returns error, then user-friendly message explains issue and suggests resolution **Priority**: Must Have **Dependencies**: Stripe API integration, email service (SendGrid) --- ### FR2: Digital Wallet Support (Apple Pay / Google Pay) **Description**: Enable payment via Apple Pay and Google Pay for faster mobile checkout **User Story**: As a mobile shopper, I want to pay with Apple Pay/Google Pay, so that I can checkout with a single tap using my saved payment method **Inputs**: - Apple Pay/Google Pay token - Purchase amount - Shipping address (from wallet if available) **Outputs**: - Payment confirmation - Order receipt **Business Rules**: - Available only on supported browsers/devices - Gracefully degrade to card entry if wallet unavailable - Auto-fill shipping address from wallet when possible **Acceptance Criteria**: - [ ] Given iPhone with Apple Pay, when user selects Apple Pay, then payment completes with Face ID/Touch ID - [ ] Given Android with Google Pay, when user selects Google Pay, then payment completes with fingerprint/PIN - [ ] Given wallet payment, when user confirms, then checkout completes in <10 seconds total - [ ] Given unsupported browser, when checkout loads, then wallet buttons hidden and card entry shown **Priority**: Should Have **Dependencies**: Stripe Payment Request API, HTTPS (required for Apple Pay) --- ### FR3: Saved Payment Methods (One-Click Checkout) **Description**: Allow customers to securely save payment methods for faster future checkouts **User Story**: As a returning customer, I want to save my payment method, so that I can checkout with one click on future purchases without re-entering my card **Inputs**: - "Save payment method" checkbox selection - Customer account (must be logged in) - Payment method details (tokenized by Stripe) **Outputs**: - Payment method saved to customer account (Stripe token stored) - Display last 4 digits and card brand in account **Business Rules**: - Maximum 5 saved payment methods per customer - Must be logged in to save payment method - Can set one method as default - Can delete saved methods anytime **Acceptance Criteria**: - [ ] Given logged-in customer, when they check "save payment method", then method saved after successful payment - [ ] Given returning customer, when they view saved methods, then see last 4 digits and expiration date (not full number) - [ ] Given saved payment method, when customer selects it at checkout, then auto-fills payment form - [ ] Given multiple saved methods, when customer sets default, then it pre-selects at checkout **Priority**: Must Have **Dependencies**: FR1, user authentication, Stripe payment methods API --- ### FR4: CRM Integration (Salesforce) **Description**: Automatically sync payment transactions and customer payment methods with Salesforce CRM **User Story**: As a sales rep, I want payment information automatically updated in Salesforce, so that I have complete customer transaction history without manual entry **Inputs**: - Successful payment transaction - Customer email (matches Salesforce contact) - Order details **Outputs**: - Salesforce opportunity updated to "Closed Won" - Transaction record created in Salesforce - Customer payment method status updated **Business Rules**: - Match customers by email address - Create new contact if email not found - Update opportunity within 5 minutes of payment - Store only last 4 digits of card in Salesforce **Acceptance Criteria**: - [ ] Given successful payment, when transaction completes, then Salesforce opportunity updated within 5 minutes - [ ] Given new customer, when payment completes, then new Salesforce contact created - [ ] Given existing customer, when payment completes, then transaction added to existing contact - [ ] Given CRM sync failure, when Stripe payment succeeds, then retry CRM update 3 times with exponential backoff **Priority**: Must Have **Dependencies**: Salesforce API access, webhook processing --- ### FR5: Accounting Integration (QuickBooks) **Description**: Automatically post successful transactions to QuickBooks for revenue recognition and reconciliation **User Story**: As a finance team member, I want transactions automatically posted to QuickBooks, so that I don't spend 20 hours/week on manual data entry and reconciliation **Inputs**: - Successful payment transaction - Customer details - Product/service purchased - Payment amount and fees **Outputs**: - QuickBooks invoice created and marked paid - Revenue recognized in correct account - Stripe fees recorded as expense **Business Rules**: - Post within 1 hour of successful payment - Separate revenue and Stripe fees into different accounts - Match customer to existing QuickBooks customer or create new - Handle partial refunds correctly **Acceptance Criteria**: - [ ] Given successful payment, when transaction completes, then QuickBooks invoice posted within 1 hour - [ ] Given $100 transaction with $3.20 Stripe fee, when posted, then $100 revenue and $3.20 fee expense recorded - [ ] Given full refund, when processed, then QuickBooks invoice voided - [ ] Given partial refund, when processed, then credit memo created for refund amount **Priority**: Should Have **Dependencies**: QuickBooks API integration, webhook processing --- ## Non-Functional Requirements ### NFR1: Performance **Response Time**: - Payment API calls: <500ms at 95th percentile - Checkout page load: <2 seconds - Payment processing (submit to confirmation): <3 seconds at 95th percentile **Throughput**: - Support 1,000 concurrent users during peak sales - Process 150 transactions per hour during peak load - Handle webhook processing for 200 events/hour **Testing Requirements**: - Load test with 1,000 concurrent users for 1 hour - Stress test to 2x expected peak load --- ### NFR2: Security **Authentication/Authorization**: - API keys stored in environment variables (never in code) - Use Stripe API key with minimum required permissions - Session-based auth for saved payment methods (must be logged in) **Data Protection**: - Never store raw credit card numbers (use Stripe tokens only) - All payment data transmitted via TLS 1.3 - PCI DSS SAQ-A compliance (tokenization model) - 3D Secure 2.0 enabled for high-risk transactions **Compliance**: - Complete PCI DSS SAQ-A questionnaire annually - GDPR compliant (support payment method deletion requests) - SOC 2 compliant webhook processing **Security Testing**: - Pass OWASP Top 10 security audit - Penetration testing before launch - Annual security review --- ### NFR3: Reliability **Availability**: - 99.9% uptime SLA (maximum 45 minutes downtime per month) - Graceful degradation if Stripe API unavailable **Error Handling**: - Retry transient Stripe API failures (3 retries with exponential backoff) - Display user-friendly error messages (never show raw API errors) - Log all errors for debugging and alerting **Data Integrity**: - Idempotent payment processing (prevent duplicate charges) - Webhook processing with deduplication - Transaction logging for audit trail **Monitoring & Alerting**: - Alert if payment success rate <95% over 15-minute window - Alert if average response time >5 seconds - Alert on any Stripe webhook failures - Daily reconciliation report comparing Stripe transactions to database --- ### NFR4: Usability **Checkout Experience**: - Maximum 4 steps to complete checkout (cart → info → payment → confirm) - Guest checkout option (no account required) - Auto-fill billing address from shipping address - Clear progress indicator showing checkout steps **Mobile Experience**: - Fully responsive design (mobile, tablet, desktop) - Digital wallet buttons prominent on mobile - Card input fields optimized for mobile keyboards - Minimum tap target size 44x44 pixels **Accessibility**: - WCAG 2.1 AA compliance - Keyboard navigation for all form fields - Screen reader compatible - Clear focus indicators **Error Messages**: - Specific, actionable error messages ("Card declined - try different card" not "Error 402") - Inline validation (show errors immediately, not after submit) - Error summary at top of form --- ## Constraints **Technical Constraints**: - Must use Stripe as payment processor (existing vendor relationship) - Must integrate with existing Salesforce CRM instance - Must use existing QuickBooks accounting system - Frontend must support IE11+ (legacy enterprise requirement) **Business Constraints**: - Launch deadline: June 30, 2026 (hard deadline for fiscal year) - Budget: $150K total (development + first year transaction fees) - Transaction fee budget: 3% of GMV (already factored into pricing) **Regulatory Constraints**: - PCI DSS compliance required (using SAQ-A) - GDPR compliance (right to deletion of payment data) - State sales tax collection required (out of scope for payment integration) **Resource Constraints**: - 2 frontend engineers, 1 backend engineer, 1 QA engineer - 16-week development timeline (4 sprints of 4 weeks each) - No dedicated DevOps engineer (must use existing infrastructure) --- ## Assumptions **User Assumptions**: - 60% of users will access from mobile devices - 70% of users will save payment method if offered - Users have modern browsers (Chrome, Safari, Firefox, Edge - last 2 versions) - Average transaction value: $275 **Technical Assumptions**: - Stripe API maintains 99.99% uptime (historical average) - Stripe API remains backward compatible (no breaking changes) - Webhooks delivered within 5 minutes (Stripe SLA) - Current infrastructure can handle 10x transaction volume growth **Business Assumptions**: - Transaction volume grows from 1,000/month to 5,000/month within 6 months - Cart abandonment reduces from 45% to 25% after launch - Customers willing to pay current pricing plus transaction fees - Sales team capacity sufficient for increased order volume --- ## Out of Scope **Features Explicitly Excluded**: - Cryptocurrency payments (deferred to Phase 3, market still nascent) - Buy now, pay later (BNPL) options like Klarna/Affirm (Phase 2, evaluate demand) - Subscription and recurring billing (Phase 2, not needed for MVP) - International currency support beyond USD (Phase 2, market dependent) - ACH/bank transfer payments (low demand, complex compliance) - Gift cards and store credit (Phase 3 feature) **Deferred to Future Phases**: - Advanced fraud detection rules customization (use Stripe Radar defaults for MVP) - Multi-currency pricing and display (Phase 2, after international expansion) - Invoice payment portal for net-30 terms (separate project) - Payment plan/installment options (Phase 2 after BNPL evaluation) **Platforms Not Supported**: - Internet Explorer 10 and older (< 2% traffic, not worth compatibility effort) - Native mobile apps (web-only for MVP, may build apps in Phase 3) - In-person/POS payments (separate product line, not e-commerce focus)