Senior Backend Developer

About the role

At Hello Retail we build the intelligence layer behind modern ecommerce.

Our platform turns raw product and behavioral data into real-time decisions across search, recommendations, and AI agents. The core of this is our Product Intelligence engine – a system that understands products, relationships and buying patterns based on large-scale product data.

We are now looking for a Senior Backend Developer to help scale the infrastructure powering these decisions.

You will build production systems that directly affect revenue for thousands of webshops.

What you will work on

You will design and operate the data backbone that enables our agents across our solutions.

Typical projects:

• Large-scale product ingestion pipelines
• Event processing & enrichment
• Feature generation for ML systems
• Real-time decision data models
• High-throughput service performance
• Reliability & observability of distributed systems

You will work closely with product, ML and other engineers to make intelligent decisions possible.

Tech stack

We value strong engineering fundamentals over exact tools – but relevant experience matters.

Core

• Python (primary language)
• MongoDB
• Queue / streaming systems
• Distributed workers & async processing
• APIs & microservices

Also used

• Docker, Kubernetes & cloud infrastructure
• Rust
• Caching layers
• Retrieval & search systems
• ML feature pipelines
• Large dataset processing

AI-native engineering

We actively use AI coding tools as part of daily development.

You should be comfortable working with tools such as:

• Claude Code
• Codex
• Similar LLM-assisted development environments

The ideal candidate

What we are looking for: You have built real systems – not just scripts.

You have experience with:

• Production Python systems
• Scalable data pipelines
• High-volume event processing
• MongoDB or document databases
• Queue based architectures (Kafka, RabbitMQ, SQS or similar)
• Debugging performance and failure modes
• Designing systems other engineers can safely build on

Nice to have

• Recommendation or personalization systems
• ML data preparation pipelines
• Ecommerce domain experience

What you get

• A senior engineering team with high autonomy
• Close collaboration between product, ML and engineering
• Onsite collaboration with flexible workdays
• Competitive salary
• A culture that values building technology that users actually use

We currently don't provide a VISA, so you will need to be located in Denmark to apply for the role.