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GroupFund — Committee Finance Tool

Double-entry accounting and contribution management platform for APSU 16 committee.

Next.jsTypeScripttRPCPrismaNeon PostgresPaystackClerk Auth

// problem

Business Problem

Managing committee finances across dozens of members, multiple payment methods, and strict segregation of duties required a purpose-built system — spreadsheets and manual tracking were causing reconciliation errors and compliance gaps.

// constraints

Constraints

  • Full double-entry general ledger with every transaction matched by journal entries
  • Segregation of duties: recorder, verifier, and acknowledger must be three different users
  • Paystack payment integration with webhook-driven automatic verification

// architecture

Architecture

frontend

Next.js App Router with tRPC for type-safe API calls, role-gated dashboards, and real-time GL views

backend

tRPC routers on Next.js with Prisma ORM, enforcing role-based access and SoD rules at the procedure level

database

Neon Postgres (serverless) with full Prisma schema — contributions, journal entries, drives, projects, audit log

deployment

Vercel with Neon Postgres, Paystack webhooks, and scheduled PDF report emails

Scalability Strategy

  • Generalised GL posting rules — new drive types and payment methods add without touching existing logic
  • Audit log on every mutation for full traceability
  • Monthly PDF finance reports auto-generated by cron and emailed to treasurer and president
  • Paystack webhook integration for automatic contribution verification on successful payment

Security Decisions

  • Role hierarchy with five distinct permission levels
  • Segregation of duties enforced at API level — same user cannot record and verify
  • HMAC-SHA512 Paystack webhook verification
  • Row-level access — members only see their own contribution history

Target Outcomes

  • Full double-entry GL with trial balance, income statement, and balance sheet
  • Paystack payment links with automatic webhook-driven verification
  • Supplier payment flows with automatic liability account settlement
  • Monthly automated finance reports delivered to committee leadership