Backend Developer (TypeScript/Node.js)

Mid-level Backend Developer (TypeScript/Node.js) at AYA Group, remote, full-time. Develop services for cards, accounts, operations, subscriptions, referral system, and commissions.

Develop services for cards, accounts, operations, subscriptions, referral system, and commissions — from data schema to API and background handlers. Work with monetary logic in PostgreSQL: understand functions and triggers, maintain balance invariants, design transactions, locks, indexes, and safe migrations. Develop Kafka and Pub/Sub handlers: ensure idempotency, deduplication, correct retries, and recovery after partial failures. Maintain the common Kafka controller and application event flows. Develop GraphQL and REST APIs, as well as WebSocket events. Maintain backward compatibility with independently released client applications. Integrate with card, KYC, crypto, and email providers, handle webhooks and correctly handle cases when the result of an external call is unknown. Own the subsystem end-to-end: clarify business rules, design the solution, release it, verify the result, and document important scenarios. Plan schema and data changes without downtime for critical production scenarios. Investigate application-level incidents across the chain API → DB → queue → provider and safely recover incomplete operations. Participate in code review and technical decisions; improve checks with QA, align contracts with frontend and mobile teams.

4+ years of commercial backend development with TypeScript/Node.js. Bun experience is useful but not required. Strong PostgreSQL: manual SQL, query plans, indexes, transactions, locks, and isolation levels; ability to work with a large existing schema. Experience with PL/pgSQL, triggers, and stored functions, or readiness to quickly master this layer. The database not only stores data: part of the monetary rules is implemented in it. Understanding systems with monetary state: postings and double-entry, holdings, operation statuses, multicurrency, conversions, rounding precision, reconciliation, and compensation. Experience with Kafka, Pub/Sub, or RabbitMQ: at-least-once delivery, reprocessing, deduplication, and understanding boundaries between queue, DB, and external service. Experience with GraphQL and/or REST. Bonus: schema-first approach and type code generation. Ability to safely change a live system: maintain backward compatibility, plan migration and deployment order, limit rollout, and verify results after release. Independence: ability to take a task in business terms, clarify missing rules, design a solution, and bring it to production. Engineering diligence: strict typing, static analysis, tests in the most risky places, clear verification scenarios, and up-to-date documentation. Ability to investigate failures using specific identifiers and data, distinguish facts from hypotheses, and not repeat a monetary or external operation without verifying the result. Nice to have: ClickHouse, GCP Cloud Run, Pub/Sub and Cloud Functions, Docker, GitLab CI, Redis, WebSocket, Sentry, experience in fintech or crypto products.

Full-time employment. Schedule: 5/2. Work format: remote.