Onamini
A hiring-to-payment marketplace with escrow, multi-currency wallets, and AI-assisted gig creation — built in 8 weeks
What I did
The problem
Talent marketplaces need trust infrastructure — escrow, dispute handling, verified payment release — not just a listing board. The challenge was building financial primitives (multi-currency wallets, milestone escrow, webhook-verified payments) that work correctly across three different payment providers.
The solution
An escrow system with balance validation before release, a 14-day auto-approval safeguard for stalled reviews, raw-body webhook signature verification across Flutterwave, PayPal, and Stripe, and JWT + 2FA authentication. The hiring pipeline uses a finite state machine model with explicit transitions enforced at the API level.
Key features
- Escrow with milestone-based fund release
- Multi-currency wallets (NGN/USD/GBP/EUR)
- Webhook verification across 3 payment providers
- AI-assisted gig creation via GPT-4o mini
- Real-time messaging with Socket.IO
- Finite-state hiring pipeline
Engineering highlights
★Multi-Provider Webhook Verification
Each payment provider uses a different webhook signing mechanism. Built a provider-agnostic verification layer that handles HMAC SHA-512, PayPal's webhook ID verification, and Stripe's signature headers through a unified interface with raw-body preservation.
Escrow State Machine
The escrow system enforces a strict state machine: funds are locked on project start, released per milestone on client approval, and auto-released after a 14-day safeguard window. Balance validation runs before every release to prevent overdrafts.
Engineering decisions
Raw body needed for webhook signature verification
Configured raw body capture on webhook routes while preserving parsed JSON on API routes
Webhook signatures verify correctly without breaking regular API functionality.
Technology stack
Impact
Lessons learned
Payment infrastructure is unforgiving. Every edge case — failed webhooks, partial refunds, currency conversion rounding, network timeouts — needs explicit handling.
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