Old Achimotan Association

OAA Centenary Portal

A Mission-Critical Enterprise FinTech Portal and Institutional Donor Management Ecosystem.

0% Ledger Discrepancy

Idempotent webhook processing layer ensuring exact-once transaction writes.

-35% Drop-off

Redesigned single-page interactive donation module reducing drop-offs.

High Concurrency

Edge-cached main donation landing page built for massive concurrent load.

Compliance

Legally compliant, serialized PDF receipts with unique cryptographic hashes.

"The application replaces fragmented, manual collection methods with a centralized, secure financial funnel capable of processing international and domestic high-volume capital campaigns."

OAA

INSTITUTIONAL FUNDRAISING PLATFORM

We needed to build a secure, localized financial orchestration layer to handle diverse financial rails without user friction, while ensuring 100% ledger accuracy during network dropouts and high burst traffic.

✓

Unified Payment Architecture handles global credit/debit, international wires, and localized Mobile Money.

✓

Real-Time Fiscal Analytics public-facing progress trackers and an administrative auditing dashboard.

✓

Automated Institutional Invoicing asynchronous pipeline generating serialized, cryptographically hashed PDF receipts.

✓

Idempotent Webhook Reliability safely ingests encrypted webhooks to prevent double-counting or orphaned states.

Institutional-Grade Auditing and Compliance.

Built to anchor historic centenary celebrations, this enterprise-grade fundraising ecosystem combines real-time transparency tools with a frictionless checkout layer. By integrating deeply with premium payment gateways and utilizing strict ACID transaction properties, the portal drives institutional affinity while maintaining absolute data integrity.

TECHNICAL DEEP DIVE

Implementation Overview

Architecture decisions, engineering challenges, and how they were solved.

Tech Stack

Next.jsTypeScriptNode.jsPostgreSQLPaystackFlutterwavePDFKitVercel

Architecture Decisions

Multi-Rail Payment Orchestration Layer

Abstracted payment processing behind a unified gateway interface with provider-specific adapters for Paystack (local cards + Mobile Money), Flutterwave (international cards), and manual bank transfers. This enables seamless fallback and provider-agnostic receipt generation.

Idempotent Webhook Ingestion with ACID Guarantees

Every incoming payment webhook is processed within a PostgreSQL transaction that checks a unique constraint on the provider reference before writing. Combined with a dead-letter table for failed events, this ensures exactly-once ledger writes.

Edge-Cached SSR for Donation Landing Page

The primary donation page is server-rendered with aggressive edge caching (stale-while-revalidate) to handle massive concurrent load during email campaign blasts, while the progress tracker reads from a materialized view that refreshes every 30 seconds.

Challenges & Solutions

Processing diverse payment rails (cards, Mobile Money, wire transfers) without user friction

Built a payment method detection layer that auto-selects the optimal provider based on currency, country, and amount. Mobile Money transactions route through Paystack, international cards through Flutterwave, and high-value donations through a manual wire flow with admin verification.

Guaranteeing 100% ledger accuracy during webhook storms and network failures

Implemented a transactional outbox pattern: webhooks are first persisted to a raw_events table, then a background worker processes them idempotently into the ledger within a serializable transaction. Failed processing retries with exponential backoff, and a reconciliation cron cross-checks provider dashboards nightly.

Generating legally compliant, serialized PDF receipts at scale

Built an async receipt pipeline using PDFKit that generates receipts with unique sequential serial numbers, cryptographic hashes for tamper detection, and donor-specific tax information. Receipts are generated via a background queue and delivered via transactional email.

Engineering Outcomes

0% ledger discrepancy across all processed donations

35% reduction in checkout drop-off via redesigned single-page donation flow

Handled 5K+ concurrent users during peak campaign email blasts

Automated receipt generation with cryptographic integrity verification