Senior Backend Engineer – AI / HR Tech (Category-defining European Startup)

We’re not just building another HR tool. We’re building the intelligence layer that helps thousands of teams think, decide, and grow smarter. This is your chance to build from the ground up, not just maintain what already exists.

Join us as our Senior Backend Engineer and shape the AI core that will power the next generation of work.

We’re Sloneek, a fast-growing European HR tech startup on a mission to change HR for the better. Our platform helps organizations run smoothly — managing people, data, and workflows with clarity, accountability, and a touch of AI magic. 
We’re 35+ people across Europe, working hybrid and remote, and gearing up for our next growth round. 

🧠 Your Playground (Tech Stack & Focus Areas)

You’ll work in a modern, AI-powered backend environment that blends reliability with cutting-edge experimentation:

• Language: Python 🐍 (core backend language)
• Framework: FastAPI ⚡ (high-performance, async-ready APIs)
• Database: PostgreSQL 🗄️ (relational, scalable, with some JSONB magic)
• AI Layer: LLM-based agents (OpenAI / Anthropic models) for automation, reasoning, and HR insights
• Protocols: Model Context Protocol (MCP) — powering next-gen agent integrations
• Infra: Kubernetes, Bitbucket/GitHub Actions, AWS
• Monitoring: Prometheus / Grafana stack (or alternatives you can help define)

You’ll design the architecture behind AI-assisted HR workflows, connecting structured data, human actions, and intelligent automation into one seamless experience.

💪 What You’ll Actually Be Doing

• Architect & build scalable backend systems for our core HR product using Python and FastAPI.
• Integrate AI agents into production systems — think: automated onboarding workflows, smart document handling, and insight generation.
• Design and optimize APIs that connect frontend, AI services, and internal systems.
• Collaborate cross-functionally with product, design, and AI teams to ship features that make HR simpler and smarter.
• Experiment with MCP integration, helping shape how our agents interact with live company data and user actions.
• Define standards for clean code, performance, and data security as we scale.

💡 You Might Be a Fit If You…

• Have deep Python experience, ideally with async frameworks like FastAPI or Flask.
• Know your way around PostgreSQL.
• Have built or scaled RESTful APIs that power real products.
• Are curious about AI agent design, prompt orchestration, or workflow automation — even if you’re not an ML researcher.
• Love clean architecture and care about how systems evolve, not just how they run.
• Are proactive, communicative, and comfortable in fast-moving, high-ownership environments.
• Want to be part of a team where decisions are owned, not passed around.

✨ Why Join Sloneek

• You’ll be the first  hire shaping the AI backend layer of a product used by growing teams across Europe.
• You’ll work with a mission-driven company where tech and people culture grow together.
• You’ll get autonomy, visibility, and influence — no corporate layers.
• You’ll be part of a team that values accountability, challenge, and creativity (plus good humor).
• You’ll help build something that truly changes how people work — smarter, simpler, and more human.

If you’re passionate about backend architecture, AI integration, and building from zero with real impact, we’d love to hear from you.

Let’s reinvent HR together — one smart API at a time.