Backend Engineer - Recommendation (all genders)
About You SE & Co. KG4 days ago
Hamburg, Germany or Berlin, GermanyMid Level
Responsibilities
- Develop the recommendation engine powering homepage, product, and outfit pages using Node.js and TypeScript.
- Deploy offline-trained ML models, including Matrix Factorization, Brand Similarity, and Image Embeddings, at Black-Friday scale.
- Design personalization logic for feed assembly, fallback chains, deduplication, diversity, and A/B experiments.
- Build streaming GenAI features such as the Gemini Fashion Advisor with low latency, session-state management, and efficient token-cost control.
- Own reverse-ETL pipelines that transfer model outputs from BigQuery into performant hot stores.
- Monitor recommendation coverage and business KPIs through SQS and BI systems.
- Contribute to system architecture in collaboration with the Tech Lead and take end-to-end ownership of the recommendation engine.
Requirements
- At least 3 years of experience developing performant backend services, ideally with Node.js and TypeScript; equivalent experience with Java, Go, or Kotlin is also accepted.
- Deep practical experience with Redis or Valkey data modeling, multi-level caching architectures, TTLs, invalidation, and binary formats such as Protobuf or Avro.
- Strong understanding of high-throughput systems and experience scaling APIs under strict latency SLOs to 10,000+ requests per second.
- Interest in combining backend engineering and machine learning by serving model scores, embeddings, or LLM features in production systems.
- Very good English communication skills and a data-driven, experimentation-oriented working style.
- Preferred: knowledge of recommender systems such as collaborative filtering, Matrix Factorization, cold-start handling, and diversity algorithms.
- Preferred: experience with streaming GenAI or LLM products, including chat UX, prompt caching, or guardrails.
- Preferred: familiarity with AWS serverless services, especially DynamoDB data modeling, SQS/SNS, and OpenSearch k-NN indexes.
- Preferred: performance optimization experience using clinic.js or flamegraphs and load testing with k6.
Benefits
- The company provides a benefits program linked from its benefits page.
- The role is based within ABOUT YOU’s Hamburg and Berlin locations; specific remote or hybrid arrangements are not stated.
- The company highlights an inclusive and accepting workplace, flat hierarchies, direct communication, pragmatic decision-making, team lunches, after-work drinks, company events, and informal team interaction.
Categories
About About You SE & Co. KG
ABOUT YOU SE & Co. KG operates an online fashion marketplace for European consumers and licenses commerce technology to brands via its SCAYLE platform. The group sells apparel and lifestyle products through its mobile app and aboutyou.com, and offers a cloud-based enterprise shop system under a license model to retailers. Founded in 2014 and headquartered in Hamburg, it is a publicly listed company.