Senior Backend Engineer - Payments & Fintech

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior Backend Engineer - Payments & Fintech based in Portugal. This is a high-impact backend engineering role focused on rebuilding and scaling the financial systems at the heart of a rapidly growing global platform. You will own the architecture and implementation of a canonical payments, subscriptions, billing, and entitlement platform from the ground up. The role combines deep backend engineering with complex financial workflows spanning multiple payment gateways, legal entities, and currencies. You will work closely with Finance, Operations, and technical leadership to ensure every payment, entitlement, refund, and financial record is accurate and traceable. Your work will directly improve revenue integrity, accounting accuracy, customer entitlements, and business reporting. You will also lead a careful migration from legacy systems to a reliable, auditable platform without disrupting live customers or financial operations. This is an ideal opportunity for an experienced engineer who enjoys solving complex money-system problems where correctness, reliability, and data integrity are critical.