Company Description We are one global team, guided by respect, integrity, and a passion for doing better every day. builds the platform infrastructure that powers AI inference at scale, including API gateways, authentication, billing, and multi-tenant serving. designs and builds high-performance backend systems and APIs that power intelligent applications across diverse industries. senior backend engineer highly skilled Python Developer with maintain backend platform behind our AI inference endpoints
- a multi-tenant system handling authentication, API key management, usage metering, billing and request proxy services that enable high-availability, data-intensive AI-powered solutions. The role is high-ownership and you will shape architecture decisions, raise the bar of engineering quality and build systems that are performant, secure and observable at scale. You'll collaborate with experts in AI infrastructure and data engineering to build robust, secure, and efficient systems that scale to millions of requests. API gateway, authentication, authorization, key rotation, and multi-tenant isolation. Design, implement, and optimize APIs and backend systems using Python frameworks such as primarily FastAPI (or Flask, or Django). Architect and implement usage metering, billing integration, and rate limiting for inference endpoints. Build and maintain scalable, fault-tolerant microservices for data processing and AI integration. Implement robust CI/CD pipelines, monitoring, and observability for high-performance production systems. Drive technical decisions on architecture, data modeling, and technology choices. Identify performance bottlenecks and drive improvements in reliability, scalability, and latency. Establish engineering standards for the backend codebase: testing, code review, CI/CD, and deployment practices. Degree in Computer Science, Software Engineering,



or equivalent professional experience. developing backend systems Strong proficiency in Python and at least one systems-oriented language (Go, Rust, Java, C++) , willingness to work across the current stack which includes Python (FastAPI)
- we value the right tool for the jobengineer with deep knowledge of asynchronous programming, modern Python tooling and profiling. consistency, fault tolerance, concurrency, performance and networking , data pipelines, and performance optimization. Experience with cloud infrastructure (AWS, GCP, or Azure) and container ized environments (Docker ) Kubernetes). Understanding of database design (SQL, ORMs etc.) and data modeling at scale. Fluent in English (written and verbal) and comfortable collaborating in international teams. integration of AI APIs, RAG workflows, or vector databases). modern DevOps practices, infrastructure as code, Prometheus, Grafana, OpenTelemetry) . Exposure to ML serving infrastructure (model servers, GPU scheduling, inference optimization) is a plus but not required. Comfortable occasionally touching or contributing to frontend code when necessary. Experience in stress/load-testing and evaluating performance of production systems. Strong problem-solving mindset and commitment to code quality and performance excellence. Track record of improving engineering culture: mentoring junior engineers, introducing better practices, leading technical discussions. T-Social: social initiatives (sports, community, health, ...) Hybrid work model (remote/on-site) Versátil

working hours
Customized training: access to Coursera to learn whatever you want, whenever you want Weekly language classes (English, Spanish & German) Flexible compensation plan (health insurance, meal vouchers, childcare, transport) Social fund Free access to specialist services (medical, legal, wellness) Please send CV in English.

📌 Senior Lead Back End Engineer (España)
🏢 T-Systems Iberia
📍 España