Senior Backend Developer (File Processing)

The role is about: We are a lean but growing engineering team working in the eCommerce payment processing space. As we expand, we are looking for a Senior Backend Developer to join our File Processing squad and take ownership of our pipeline migration. You will lead the transition from legacy Perl/crontab infrastructure to a modern, observable, and maintainable Python-based architecture. You will play a central role in designing, building, and operating the systems that process daily scheme files (e.g., Visa and Mastercard clearing/settlement files), replacing manual production access patterns with robust orchestration and deployment automation. In this small team, your voice carries real weight—you will help define how we build, not just what we build. Location: Remote from Portugal or Ukraine (Contractor arrangement) Reporting to: Technical Lead What you will do: Pipeline Re-architecture: Migrate and re-architect legacy Perl batch jobs and crontab pipelines into modern Python-based services. Workflow Orchestration: Design and implement orchestration using Prefect or Airflow , including alerting, observability dashboards, and safe job re-run capabilities. Modern Observability: Instrument services with structured logging and metrics (CloudWatch, or Grafana) to eliminate the need for direct production server access. Data Layer Ownership: Manage the data layer for file ingestion: landing raw scheme files to S3, parsing/transforming them, and persisting to PostgreSQL or RDS for reconciliation. Financial Domain Logic: Process and reconcile payment scheme files (clearing, settlement, chargebacks) from card schemes and acquirers. Engineering Standards: Contribute to architecture decisions, write technical documentation, and establish best practices across the team. What we need: Python Seniority: 5+ years of production-grade Python expertise. Orchestration Mastery: Proven experience in job orchestration using Prefect or Airflow . AWS Depth: Solid experience with AWS services, specifically S3, Lambda, SQS, and ECS . Data & Databases: Strong experience with relational databases (MySQL/PostgreSQL) and processing large-scale file-based data. Clean & Intentional Code: We value deep engineering logic over AI-generated snippets. You should be a "clean code" advocate who can explain the reasoning behind every line you ship. Curiosity for Product: You care about the "why" behind a feature. You are interested in how a product works for the end-user and the business. English Proficiency: Strong English communication skills—both written and verbal. Nice to Have: Familiarity with payment scheme file formats (Visa BASE II, Mastercard IPM, or equivalent). Experience reading and refactoring Perl or legacy scripting languages. Knowledge of payment clearing, interchange, and reconciliation processes. Keystone AI com/privacy-policy" rel="nofollow noreferrer noopener" class="external"> Hiring Process: Step 1: Initial Interview – A 30–40 minute online interview with a Talent Acquisition Partner where we explore your experience, career goals, motivations, and overall fit for the role. This is your chance to walk us through your background and highlight your key achievements. Step 2: Live Technical Assessment Interview: A live coding challenge with our team lead and designated field technical experts to assess your technical skills, the interview time will be from 60-90 minutes. Step 3: Final Discussion – A 30-minute conversation with the CTO, CPO, Team Lead, and Talent Acquisition Partner to clarify any remaining questions about responsibilities, the domain, or the scope of the role. This is also your opportunity to learn more about our culture and expectations. The perks of being a Keystone AI er: Grow with Us: Annual Learning Budget for professional development (eligible after probation)—because your growth is our growth. Celebrate Together: We bring colleagues from all offices together for unforgettable company celebrations. Global Collaboration & Events: Opportunities to participate in international company events and initiatives, connecting with colleagues from all regions and contributing to a truly global community This is a fully remote role for candidates based in Portugal or Ukraine. Let's embark on a journey to redefine the landscape of payments together. We're not just offering a role; we're inviting you to be a part of something bigger. Join our team, and let's innovate, disrupt, and lead the future of payments. Together, we can make an impact that resonates. Welcome to the team! Please review our Privacy Policy to understand how we process your personal data during the recruitment process: Keystone AI com/privacy-policy" rel="nofollow noreferrer noopener" class="external">https:// Keystone AI com/privacy-policy Keystone AI com/privacy-policy" rel="nofollow noreferrer noopener" class="external"> Originally posted on Himalayas