Tech Lead

Backend Tech Lead - AI / RAG Platform

Berlin | Hybrid
TypeScript / Node.js | RAG | Data Ingestion | Search & Retrieval

We're working with a fast-growing AI software company that is looking for a Backend Tech Lead to take technical ownership of a core part of its AI platform.

This is a hands-on technical leadership role for someone who enjoys solving complex backend problems, setting architectural direction and still being close to the code.

The platform processes large volumes of unstructured enterprise data and makes that information searchable and usable through AI. You'll own the backend architecture behind the ingestion, processing and retrieval layer, helping the team improve how data moves from raw documents through to high-quality AI retrieval.

What you'll be doing

• Own the technical direction and architecture of a core backend/RAG platform
• Design and improve data ingestion pipelines handling unstructured content across PDFs, Office documents, HTML, email and other formats
• Build scalable backend services using TypeScript and Node.js
• Improve retrieval quality across embeddings, vector search and RAG-based systems
• Work across technologies including PostgreSQL, Elasticsearch and vector databases such as Qdrant
• Design systems for scale, reliability, failure handling and efficient processing
• Make architectural decisions around service boundaries, indexing strategies and data processing
• Build within a multi-tenant SaaS environment, with strong consideration for data isolation and enterprise security
• Set engineering standards, review technical designs and mentor other backend engineers
• Remain hands-on with implementation while driving longer-term technical direction

What we're looking for

• 7+ years of backend software engineering experience
• Strong commercial experience with TypeScript and Node.js
• Previous experience acting as a Tech Lead, Staff Engineer, Principal Engineer or similar technical leadership role
• Strong experience building data ingestion or unstructured data processing pipelines
• Experience with databases, indexing and retrieval technologies such as PostgreSQL, Elasticsearch, Qdrant or similar
• Production experience with embeddings, vector search, semantic search or RAG
• Strong system design skills, particularly around scalability, reliability and distributed backend systems
• Experience working within multi-tenant SaaS architectures
• Comfortable balancing hands-on engineering with technical leadership

Why join?

You'll be joining an ambitious AI business at a point where the underlying platform is scaling rapidly. Rather than maintaining a mature system, you'll have the opportunity to shape how a critical part of the architecture evolves and establish the technical standards that support its next stage of growth.

If you're a senior backend engineer who wants genuine architectural ownership while remaining hands-on, we'd love to hear from you.

Sphere Digital Recruitment currently have a variety of job opportunities across digital so feel free to get in touch with us to find out how we can help you. Please take a look at our website.

Sphere is an equal opportunities employer. We encourage applications regardless of ethnic origin, race, religious beliefs, age, disability, gender or sexual orientation, and any other protected status as required by applicable law.

If you require any adjustments or additional support during the recruitment process for any reason whatsoever, please let us know.