Senior Software Engineer - Infrastructure

All3 is transforming how buildings are conceived, developed, and delivered. We combine AI-powered design with robotic prefabrication and on-site assembly to build custom architecture at the cost and speed of mass production — unlocking even the most complex sites.

We’re currently seeking a Senior Software Engineer to join our team and help connect architectural and structural modules into one seamless system, designing intuitive interfaces and efficient backend services.

• Own FastAPI-based services: design, build, and evolve business APIs for design options and scoring pipelines keeping schemas and migrations healthy;
• Build and harden async workflows (Celery/Redis) for heavy calculations, model parsing, and future broker integrations ensuring observability and retries;
• Integrate third-party platforms (Autodesk APS and Speckle - today, brokers - tomorrow) including auth, token handling, and data ingestion/conversion;
• Develop API Gateway patterns to serve multiple client types (web app, partner services, automation) with clear versioning and access control;
• Optimize data processing for geometry/area/cost calculations (pandas/numpy), exports (XLSX), and caching strategies;
• Collaborate with product/architecture teams on system design, SLAs, and security; review code and raise quality bars;
• Improve CI/CD, containerization, and runtime reliability (Docker, health checks, monitoring/logging).

• Strong Python 3.11+ with production FastAPI (or similar async frameworks) and Pydantic v2;
• Confident with relational data modeling and async SQLAlchemy;
• Comfortable driving Alembic migrations and query performance on PostgreSQL;
• Experience building async/background jobs with Celery/Redis or equivalent queuing systems;
• Solid REST API design skills: auth (API keys/JWT), pagination/filtering, OpenAPI/validation, versioning;
• Hands-on with Docker-based delivery, Git/CI pipelines, and runtime observability (logging/metrics/tracing);
• Data-handling skills: pandas/numpy for calculations; generating reports/exports (e.g., XLSX);
• Bonus: BIM/3D data flows (Autodesk APS, Revit/IFC, Speckle) and messaging/broker integrations;
• API gateway patterns (Kong/Traefik/NGINX) and event-driven architectures.

• Chance to be a part of a large-scale project;
• Team driven by impactful cause;
• Hybrid format of work with spacious office in New Belgrade;
• Private health insurance including dental;
• Language courses;
• Flexible working schedule;
• 20 days of annual leave.