Backend разработчик

Gismart is a mobile app developer with award-winning products in Health, Wellness, Utilities, and Music, with over 1 billion downloads worldwide. Its apps help people build a healthy lifestyle that is sustainable and enjoyable.

• Build the orchestration core as a unified layer over multiple AI providers with failover, retries, rate limiting, and rapid onboarding of new models;
• Own API contracts consumed by the Flutter client, including stability, versioning, and clear error handling;
• Build the media pipeline for storing and delivering generated assets through S3/CDN with cost control;
• Maintain system reliability during paid-traffic spikes through metrics, tracing, and per-provider alerting;
• Implement usage accounting with per-generation cost tracking, integration with the core billing service, and idempotent charging without double-spend or race conditions;
• Design the asynchronous generation pipeline with long-running job queues, provider webhooks, delivery guarantees, and failure recovery.

• 4+ Years of commercial backend development experience;
• Strong experience with Go, or solid backend expertise in Java, Kotlin, C#, Rust, or TypeScript with willingness to transition to Go from day one;
• Experience designing and building backend services operating under real production load;
• Solid understanding of architectural trade-offs and decision-making;
• Strong API design skills with REST and gRPC;
• Experience building maintainable, backward-compatible APIs consumed by mobile applications;
• Experience integrating third-party APIs with retries, idempotency, rate limiting, and graceful recovery from partial failures;
• Strong PostgreSQL knowledge, including transactions, isolation levels, indexing, and data consistency;
• Experience with asynchronous processing and messaging systems such as SQS, Redis, Kafka, or Temporal;
• Experience with AWS or GCP, Docker, and modern CI/CD pipelines;
• Practical experience with observability, including metrics, logging, tracing, and independent debugging of production issues;
• Ability to quickly ramp up on an existing codebase and extend it rather than rewrite it from scratch;
• Comfortable working in a fast-paced, iterative pre-PMF environment with evolving priorities;
• Ready to take ownership as the first Product Engineer and drive solutions across the entire development lifecycle;
• Nice to have: VictoriaMetrics, Grafana, Sentry, generative models, billing and payment systems, media pipelines, B2C products with paid acquisition, unit economics, SSE/WebSocket, Kubernetes, Kafka, early-stage startup experience, personal projects shipped to real users.

• 70% Of professional development courses and 100% of English language courses are covered;
• Health insurance, sports reimbursement, and psychotherapy reimbursement;
• 18 Days of paid vacation, 3 paid personal days, plus 1 additional day for each year at Gismart;
• Public holidays follow Ukrainian or Polish holiday calendars; employees in other locations receive 12 public holidays per year;
• 100% Sick leave compensation;
• Corporate devices are available, or monthly depreciation compensation is provided for using a personal laptop;
• Coworking space costs are covered.