Senior Backend Engineer - Search & Discovery (all genders)
About You SE & Co. KG4 days ago
Hamburg, GermanySenior
Responsibilities
- Develop and enhance the ABOUT YOU search engine, including query understanding, entity resolution, semantic vector search, and behavioral re-ranking.
- Build and maintain search-index pipelines for entities, synonyms, and k-NN product vectors using data from BigQuery and OpenSearch.
- Integrate LLMs and embedding models such as Gemini and Vertex AI with caching and fallback mechanisms under strict latency constraints.
- Improve search quality through golden lists, regression suites, and continuous A/B experiments.
- Collaborate on architecture with the Tech Lead and work closely with Data Analysts, Engineers, and Product Managers.
- Investigate the reasons behind search results and translate findings into concrete technical improvements.
Requirements
- At least 5 years of experience developing scalable, low-latency backend APIs.
- Strong experience with Node.js and TypeScript, or equivalent experience with Java, Go, or Kotlin.
- Deep practical experience with Elasticsearch or OpenSearch, including mappings, custom analyzers, percolators, and scoring functions.
- Strong algorithmic understanding of ranked data, including result merging, deduplication, score combination, and balancing latency against result quality.
- Interest in connecting backend engineering and machine learning by deploying model scores, embeddings, or LLM features in production systems.
- Very good English communication skills and a pragmatic, data-oriented approach with curiosity for new problems.
- Basic knowledge of information retrieval and NLP is desirable.
- Experience with vector search, k-NN/HNSW indexes, SigLIP embeddings, and optimizing recall versus latency is desirable.
- Practical LLM engineering experience, such as prompt caching, timeout budgets, or Datadog LLM observability, is desirable.
- Familiarity with BigQuery, dbt, Dagster, and related data pipelines is desirable.
Benefits
- The company promotes an inclusive and accepting workplace where different backgrounds and perspectives are valued.
- The role is based at ABOUT YOU locations in Hamburg and Berlin.
- Employees can participate in team lunches, after-work drinks, company events, and informal coffee breaks.
- The company emphasizes flat hierarchies, direct communication, pragmatic decisions, and short approval paths.
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.