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Sofia · Hybrid

Senior Backend Engineer (.NET and Python)

Avenga is an international engineering firm helping businesses operate with AI at the core. With 6,000+ experts worldwide, we combine engineering expertise with AI-native thinking to turn ambitious ideas into real-world impact across industries, technologies, and markets.

At the core of the role

We’re looking for a hands-on engineer to help shape an enterprise platform from an early stage, building and maintaining the backend services, APIs, and cloud infrastructure that power AI-driven solutions.

You’ll focus on security, access control, policy enforcement, observability, and reliability at enterprise scale, while leveraging automation and modern DevOps practices to streamline delivery.

Your work will have a visible impact from the first weeks, with opportunities to contribute to the platform itself and later support its deployment with enterprise clients.


Core skills you’ll bring

  • 6+ years of professional backend engineering, with production experience in both C#/.NET and Python, and strong in at least one of them.

  • API and distributed-systems design: REST and gRPC, asynchronous processing and queues, idempotency, relational and NoSQL data stores.

  • Production experience on at least one major cloud (Azure, AWS or GCP) and working experience with a second, including Terraform or equivalent, containers and Kubernetes.

  • Security fundamentals: OAuth 2.0 and OpenID Connect, secrets, least privilege, network isolation, data protection.

  • Observability experience: OpenTelemetry, Prometheus/Grafana or a cloud-native equivalent.

  • Spec-driven development as your normal way of working: specifications, interface contracts and acceptance criteria written before code; daily use of AI coding agents (for example GitHub Copilot, Claude Code or Cursor, with tools such as GitHub Spec Kit or Kiro); rigorous review and testing of generated code.

  • A working understanding of LLM applications: model APIs, streaming, tool calling. You do not need to be an AI specialist.

  • Fluent English: you can explain a design to a client's CTO or security team and defend it.

Nice-to-have

  • API gateways and reverse proxies: Azure API Management, YARP, Envoy, LiteLLM or similar.
     Policy engines such as Open Policy Agent, and audit-grade logging.

  • High-throughput streaming APIs.

  • Regulated industries (financial services, pharma, telco).

  • Consulting or client-facing delivery; contributions to open-source projects.

The impact you'll create

  • Design and build backend services and APIs in C#/.NET and Python: an AI gateway, access control, rate and spend limits, failover and upgrades.

  • Integrate with enterprise identity, secrets management and the AI services clients already use on Azure, AWS and GCP.

  • Build for performance and resilience: streaming, concurrency, caching, load testing and graceful degradation.

  • Store and serve audit, usage and cost data reliably.

  • Build cloud infrastructure as code and CI/CD pipelines, with supply-chain security.

  • Instrument everything: traces, metrics and logs, with the alerts and runbooks that production needs.

  • Work spec-first: write the specification and acceptance criteria, implement with AI coding agents, then review and verify what they produce.

  • Write and review production-grade code, and contribute to technical proposals.

 What supports your journey

People are at the core of Avenga. We provide equal opportunities regardless of race, ethnicity, gender identity, sexual orientation, disability, age, religion, or any other characteristic. We are committed to a respectful environment where everyone can be themselves, share their ideas, and feel that they belong.

Location
Sofia
Remote status
Hybrid
Technology
.NET
Seniority
Senior-level

Take the first step toward your career at Avenga

APPLICATION

Send your CV to tell us about your core skills and what you're looking for next.

TALENT CALL

Meet our Talent team to talk about your goals and experience while exploring our culture and the way we work.

TECHNICAL INTERVIEW

We'll explore your experience, strengths, and approach to work to see what we can build together.

CUSTOMER INTERVIEW

For some roles, you'll meet our customers to understand the outcomes your expertise can help create.

WELCOME TO AVENGA

An offer is just the beginning. We welcome you to put your expertise into action and shape what's next together.

Sofia · Hybrid

Senior Backend Engineer (.NET and Python)

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