Senior Fullstack Engineer, Payments

Alt is unlocking the value of alternative assets, starting with the $5 B trading-card market. They are seeking a Senior Fullstack Engineer to build the financial engine of their platform, focusing on custom double-entry ledger systems, lending infrastructure, and payment integrations.

Responsibilities:

• Build and maintain our custom-built double-entry ledger system to ensure every cent is accounted for across the platform
• Design and scale our lending products—from the logic of credit disbursements to the automated lifecycle of loan management
• Design and implement robust integrations with payment gateways and banking partners, ensuring 99.99% reliability and seamless reconciliation
• Create high-trust user interfaces for payments and lending that make complex financial actions feel simple, transparent, and secure
• Make thoughtful trade-offs between rapid feature shipping and the uncompromising correctness required for financial systems
• Level up the team through rigorous code reviews, technical documentation, and mentorship

Requirements:

• 5+ years of experience with a heavy focus on backend systems (Python, Postgres, AWS) and a proven ability to build modern frontends (React, TypeScript)
• Fintech or Payments experience: You've worked with ledgers, payment processors, or lending products and understand the complexities of moving money
• Database Mastery: You are an expert in SQL and relational database design—you know how to write a transaction that won't fail under load
• Fullstack Ownership: A track record of taking a complex financial feature from a technical design doc all the way to a polished UI in production
• Experience with distributed systems, credit/risk modeling, or the alternative asset space