Senior Software Engineer – Payments, Credit Card & Alternative Payments

This is a fully remote position, open to applicants in Serbia.

📋 Description

• Develop and sustain scalable, fault-tolerant services that manage real-time authorization, batch clearing, and settlement workflows.

• Create and uphold integrations with acquiring banks, card networks (Visa, Mastercard, Amex, Discover), payment gateways, fraud prevention providers, and tokenization services.

• Implement reliable routing logic, retry strategies, and failover mechanisms across card network connections.

• Ensure transaction idempotency and effective state management throughout the entire card payment lifecycle.

• Support 3D Secure (3DS2) and Strong Customer Authentication (SCA) processes.

• Establish and maintain card vaulting and tokenization solutions in compliance with PCI DSS standards.

• Build and uphold integrations with a diverse range of Alternative Payment Methods (APMs), such as digital wallets (PayPal, Apple Pay, Google Pay), bank transfers (ACH, SEPA, instant bank pay), Buy Now Pay Later (BNPL) services, prepaid and voucher methods, as well as regional local payment methods across key markets.

• Design adaptable and extensible integration patterns to facilitate the swift onboarding of new payment methods and providers.

• Manage the distinct lifecycle requirements of each payment method, including asynchronous notifications, delayed confirmations, refund processes, and currency/settlement nuances.

• Collaborate with Product teams to assess and prioritize new APM integrations based on market needs and demand.

• Construct and maintain automated reconciliation pipelines that align authorization, clearing, and settlement records across both card and APM payment channels.

• Reconcile internal ledgers against reports from acquirers, networks, and Payment Service Providers (PSPs); identify and highlight mismatches, duplicates, and missing transactions.

• Develop protective measures to avert revenue loss and guarantee consistency in ledgers at scale.

• Ensure all financial systems are prepared for audits and comply with internal financial regulations.

• Create and maintain payment reporting systems that encompass authorization rates, settlement reconciliation, interchange and fee breakdowns, APM conversion rates, and chargeback/dispute metrics.

• Implement alerting systems based on thresholds for authorization rate declines, anomaly patterns in declines, settlement mismatches, volume spikes, and changes in chargeback ratios across all payment methods.

• Contribute to internal financial dashboards that aid in cost optimization, risk monitoring, and visibility into financial performance.

• Participate in on-call rotations and incident response for payment-critical systems.

• Develop systems that adhere to PCI DSS, card network operating regulations, data encryption and tokenization standards, and regional mandates.

• Assist in the secure management of sensitive payment data across card and APM flows.

• Support audit processes and financial compliance reviews as necessary.

• Integrate with fraud detection and risk scoring systems across card and APM payment flows.

• Implement components for chargeback and dispute workflows, including evidence submission and representment support.

• Establish safeguards and monitoring systems for detecting fraud patterns across different payment methods.

• Write clean, thoroughly tested, and well-documented code with a strong emphasis on reliability, observability, and accuracy.

• Actively engage in code reviews, technical design discussions, and architectural decisions.

• Contribute to best practices for designing distributed systems, observability, incident response, and maintaining financial data integrity.

• Mentor junior engineers and foster a culture of high trust and high accountability within the engineering team.

⛳️ Requirements

• Minimum of 5 years of software engineering experience.

• At least 2 years of experience working with production payment processing systems.

• Practical experience with card payment processes: authorization, clearing, settlement, reconciliation, and chargebacks.

• Experience in integrating with or developing for one or more APM providers (wallets, bank transfers, BNPL, local payment methods).

• Strong understanding of the four-party (Visa/Mastercard) and three-party (Amex/Discover) models, including interchange, BIN logic, MCC codes, AVS, CVV, and 3DS/SCA.

• In-depth knowledge of distributed systems: idempotency, eventual consistency, fault tolerance, and high availability.

• Proficiency in designing and utilizing RESTful and/or event-driven APIs within a payments context.

• Familiarity with PCI DSS and foundational principles of payment data security.

• Strong debugging and incident response capabilities in complex, high-volume financial systems.

🏝️ Benefits

• Comprehensive health insurance.

• Paid time off.

• Flexible work arrangements.

• Opportunities for professional development.