Urgent: Backend Dev for WhatsApp Crypto Payments (Node.js/Python)

I'm seeking an experienced backend developer to work on a mission-critical crypto payment integration using NOWPayments.

Key Tasks:
- Implement NOWPayments API to generate dynamic USDT addresses (documentation provided)
- Encrypt both user personal data and transaction details using AES-256
- Patch SQL injection and XSS vulnerabilities
- Optimize Firestore to achieve response times under 100ms
- Manage webhook failures and retries

Tech Stack:
- Node.js (preferred) or Python
- Firebase
- NOWPayments/Stripe

Ideal Skills and Experience:
- 5+ years in backend development
- Basic experience with crypto payments
- Expertise in security hardening (OWASP Top 10)
- Availability for daily stand-ups (GMT+5)

Please only apply if you meet the above criteria.