Senior Python Engineer – On-site, Warsaw

Square One Resources is seeking a Middle/Senior Backend Engineer to design, build and own business-critical production systems working on scalable backend services and AI-native solutions.

• Strong senior-level backend engineering experience in production systems.
• Strong Python skills and ability to design clean, maintainable backend code.
• Good distributed systems judgment: concurrency, failure handling, data consistency, async work, and service boundaries.
• Hands-on experience with cloud infrastructure such as AWS, GCP, or Azure.
• Comfort with database schema design and performance tuning for real-time and high throughput scenarios.
• Security-conscious engineering approach for enterprise-grade requirements and sensitive data.
• Ability to go from problem statement to design to production rollout with real ownership.
• Clear written and verbal communication skills.
• AI-native working style using AI tools like Codex and Claude Code to improve workflows.

Nice to have:

• Experience with TypeScript.
• Familiarity with AI Agents / Agentic AI, LLM / GenAI, RAG.
• Experience with microservices.

• Design and ship backend services, APIs, data flows, and background processing for production systems.
• Turn vague requirements into concrete technical plans, trade-offs, and execution.
• Own services after launch: reliability, observability, performance, and incident follow-through.
• Instrument what you ship and use production signal to iterate.
• Make sound decisions around system boundaries, data models, interfaces, and scaling paths.
• Work closely with product, frontend, and platform engineers to deliver end-to-end outcomes.
• Improve engineering leverage with AI tooling, automation, and internal workflows.
• Raise the quality bar through code review, design review, and pragmatic technical leadership.