We’re building financial infrastructure where a duplicated payment or a ledger that doesn’t balance is a serious incident. We need a fullstack engineer with deep backend and payments experience, who works with AI agents every day and takes full responsibility for what ships.

What You’ll Do

• Build and own high-performance backend services in Node.js and TypeScript for payment flows, including asynchronous workflows and webhook processing
• Integrate with external fintech APIs and handle their real-world behavior: retries, timeouts, out-of-order events, and partner downtime
• Design idempotent payment processing and transaction handling on PostgreSQL that holds up under heavy concurrency
• Build and maintain immutable ledger and reconciliation logic so the numbers always add up
• Deliver the frontend for these features in React.js and TypeScript, and make system design decisions across the stack
• Design and run AI orchestration and multi-agent workflows, including task delegation, context management, and validation of agent outputs
• Use AI tools and agents across coding, debugging, testing, documentation, and code review
• Verify everything AI produces before it reaches production. You own the result, whoever or whatever wrote the first draft
• Raise blockers, risks, and unclear requirements early with the team instead of guessing

• Expert-level experience building high-performance backend systems with Node.js and TypeScript, including asynchronous workflows and webhook engineering
• Hands-on experience integrating external fintech APIs in production
• Expert knowledge of PostgreSQL transactions, isolation levels, locking, and concurrency
• Proven experience designing idempotent payment processing
• Strong system design skills
• Good knowledge of financial systems: transactions, immutable ledgers, and core accounting concepts (double-entry, balances, settlement)
• Working familiarity with BaaS, CaaS, Open Finance, and reconciliation
• Solid frontend skills in React.js and TypeScript, able to deliver features end to end
• Hands-on experience with AI orchestration and multi-agent workflows, including managing context across concurrent agent tasks
• Daily, practical use of AI tools and agents, with a real example of catching an AI mistake before it shipped
• Proficient English communicator experienced in collaborating across distributed, remote teams

Nice to Have

• Experience with payment providers, card networks, or banking partners
• Background in compliance-heavy environments (audit trails, PCI, KYC/AML)
• Experience with agent context files (e.g., CLAUDE.md-style) and persistent-memory tooling for agents

Apply via hr@miyagami.com or DM us via Miyagami Zalo: 0905 886 456. We look forward to having further discussions with you. Thank you.