Crypto Payment Gateway Integration for Marketplace (React + Node/Express)

Description:
We are looking for an experienced Web3/payment engineer to integrate a crypto payment checkout gateway into our existing marketplace platform.
Our stack is React frontend + Node/Express backend (marketplace architecture). We need someone who can deliver a secure, clean, and production-ready integration with clear documentation.
Scope of Work:
* Integrate a crypto payment provider into checkout flow
* Build backend payment endpoints + webhook handlers
* Verify payments and update order/transaction state
* Handle edge cases (expired payments, under/overpayment, failed confirmations, duplicate webhooks)
* Implement secure secrets/config management
* Add logs and basic monitoring for payment events
* Provide technical documentation + handover
Required Experience:
* Proven crypto payment integrations (Coinbase Commerce / BitPay / NOWPayments / Stripe crypto / similar)
* Strong Node.js/Express + React experience
* Solid webhook security and idempotency knowledge
* Production payment reliability mindset
Nice to Have:
* Marketplace/e-commerce checkout experience
* Stablecoin and multi-chain knowledge
* Experience with Sharetribe-style platforms
Deliverables:
1. End-to-end crypto checkout integrated
2. Webhook verification + transaction sync
3. Admin-visible payment status mapping
4. Deployment/config guide
5. Test checklist + post-launch support window
To Apply, Please Include:
* 2-3 relevant projects with links
* Which payment provider you recommend and why
* Estimated timeline (MVP + production hardening)
* Your approach to webhook reliability and security
* Your timezone and weekly availability
Engagement:
* Remote, flexible
* Start: ASAP
* Potential for long-term work Show More