Backend Developer

Remote senior 14 days ago full-time

PythonFastAPIPostgreSQLReactTypeScript

Develop resilient backend services for processing financial transactions;
Integrate and maintain multiple payment service providers (PSP);
Design payment routing, cascading, and retry mechanisms;
Develop recurring payments, trial periods, rebills, dunning, and subscription management;
Develop idempotent APIs and protection against duplicate request processing;
Handle webhooks and implement data reconciliation with PSP;
Establish auditing, logging, tracing, monitoring, and alerting for payments;
Participate in PCI DSS certification and preparation of technical documentation;
Develop and integrate payment user scenarios using React/TypeScript;
Write automated tests and participate in code reviews.

5+ years of commercial experience in Python development;
Production experience with FastAPI and Pydantic v2;
Strong knowledge of SQL and PostgreSQL;
Understanding of ACID, transactions, and concurrent data access;
Experience in developing high-load and resilient services;
Practical experience integrating multiple PSPs;
Understanding of the full payment lifecycle: from creation to refunds and chargebacks;
Experience with recurring payments, payment routing, and cascading;
Experience with PSP tokens, network tokens, and card-on-file payments;
Experience handling webhooks and reconciliation;
Practical experience participating in PCI DSS certification;
Commercial experience with React 18 and TypeScript;
Experience with message queues, event-driven architecture, 3-D Secure 2, SCA, and payment analytics is a plus.

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