Senior Backend Engineer – Payments & Fintech (French Speaker)

About the Role We are looking for a Senior Backend Engineer with strong experience in payments and fintech environments to join a fast-growing company building payment infrastructure products. You will work on complex payment flows, PSP integrations, recurring billing, fraud prevention, chargebacks, transaction routing and payment optimization. French fluency is mandatory for this role. Tech Stack Node.js TypeScript AWS PostgreSQL APIs Microservices Responsibilities Develop and maintain integrations with multiple Payment Service Providers (PSPs). Build and improve recurring payment and subscription billing systems. Develop payment routing and transaction optimization features. Work on fraud prevention, chargeback management and transaction monitoring tools. Improve the reliability, scalability and performance of payment systems. Collaborate with Product and Engineering teams on new payment-related features. Participate in architecture discussions, code reviews and technical decisions. Requirements Mandatory 5+ years of backend development experience. Strong expertise in Node.js / TypeScript. Previous experience in payments, fintech or payment infrastructure. Experience integrating PSPs and payment gateways. Strong understanding of: Payment Processing PSP Integrations Acquiring Recurring Billing Chargebacks Fraud Prevention Payment Routing Transaction Lifecycle Fluent French speaker. Nice to Have Payment Orchestration experience. Multi-PSP environments. Smart Routing and Cascading. High-Risk Payments. Subscription businesses. Experience with providers such as Stripe, Adyen, Checkout.com, Nuvei, Emerchantpay, Trust Payments or similar. Profile Hands-on engineer. Startup mindset. Strong problem-solving skills. Comfortable working autonomously. Passionate about building reliable payment systems. Details Freelance mission. Long-term collaboration. Remote. Immediate start preferred. ⚠️ Applications without direct payment or fintech experience will not be considered.