Senior Backend Engineer

We’re hiring: 5 Senior Backend Engineers — Payments & Core Ledger (Remote, Spain) 💳⚡ Build the financial spine for the next generation of regulated prediction markets and digital gaming. We are scaling the core banking and payments platform for a fast-growing New York fintech. The company develops dedicated neobanking, wallet, and settlement infrastructure powering high-volume US prediction markets and licensed gaming operators. We have 5 open seats for Senior Backend Engineers (Payments & Ledger) based anywhere in Spain. In this seat, you will own immutable double-entry ledgers, design automated reconciliation engines, integrate instant banking rails, and architect distributed systems where zero financial drift is tolerated. The Breakdown - Role: Senior Backend Engineer (Payments & Core Ledger) - Openings: 5 seats available - Location: 100% Remote (Spain-based) - Team & Collaboration: Partnering directly with a fast-moving New York engineering and product organization - Core Tech: Java, Spring Boot (or Go/distributed systems), PostgreSQL, Kafka / Event Streaming, Redis, Docker/K8s - Domain: Core Banking, Real-Time Rails, Double-Entry Ledgers, Settlement, US Regulated Gaming / Prediction Markets What You’ll Do - Design and maintain ultra-reliable, high-concurrency ledger systems handling wallet deposits, live prediction market trading, and instant payouts. - Implement robust double-entry accounting models, ensuring auditability, immutability, and zero reconciliation discrepancies. - Integrate US payment rails, bank sponsor APIs, debit card issuance, and automated clearing networks. - Enforce strict transactional integrity, idempotency, and concurrency controls across distributed microservices. - Collaborate asynchronously and during US East Coast overlap hours with New York leadership. What You Need - 5+ years of backend engineering experience building mission-critical, high-throughput distributed systems. - Deep hands-on experience in Payments, Core Banking, Double-Entry Ledgers, or Regulated iGaming / Sportsbooks. - Mastery of Java / Spring Boot (or modern distributed Go/Node), relational databases (PostgreSQL locking, isolation levels, indexing), and event streaming (Kafka / RabbitMQ). - Familiarity with distributed transaction patterns (Outbox pattern, Sagas, idempotency keys). - Based in Spain with strong professional English proficiency. 👉 Apply here: https://app.refery.io/r/kbd42