Senior Backend Developer for Crypto Exchange API Architecture

We're building Africa's B2B2C financial infrastructure. A multi-tenant platform that lets partners (Fintechs, Banks, Neobanks) offer crypto and fiat services under their own brand. Role Description: As a senior backend developer to lead the engineering and the technical architect of our platform. You'll own the API layer, multi-tenant core, Liquidity Provider integration pattern and set the standards every engineer after you follows. You'll shape the codebase, not just contribute to it. You will collaborate closely with front-end developers and product managers to deliver new features, improve security, and enhance overall system reliability. This is a full-time remote / hybrid role. What You'll Do: • Design and build the core API architecture (Node.js/TypeScript, PostgreSQL with RowLevel Security for multi-tenancy) • Implement the LP Adapter Pattern: requestQuote → executeQuote → getStatus across primary and backup LPs. • Build the RFQ-based trading engine for launch; design the architecture to support order book trading in a future phase. • Design the internal ledger and transaction lifecycle (idempotent, auditable, reconcilable) • Set up CI/CD, code review standards, and engineering culture for the team • Architect WebSocket infrastructure for real-time market data (1-second sampling, standard candle intervals) • Collaborate with PM to translate functional specs into sprint-ready technical tickets • Make build-vs-buy decisions and own vendor integration architecture Qualifications: • 5+ years backend engineering, at least 2 in a lead/architect role  • Deep Node.js/TypeScript. This is the stack, not negotiable  • PostgreSQL expertise including advanced features (RLS, partitioning, JSONB, migrations)  • Experience designing REST APIs consumed by multiple clients (partner dashboards, mobile apps, admin tools) • WebSocket implementation experience (real-time data feeds)  • Strong opinions on code structure, testing, and deployment.  • Experience with message queues (Redis/BullMQ, RabbitMQ, or similar) for async processing Nice to Have: • Fintech or financial services backend experience (payments, trading, custody) • Experience integrating with external trading APIs or liquidity providers • Multi-tenant SaaS architecture (B2B2C or white-label platforms) • Familiarity with MPC custody APIs What We Offer: • Founding Equity consideration • CTO position consideration • Build the financial rails that Africa's next-gen fintechs will run on