Backend Engineer - Recommendation (all genders)

Location: Hamburg or Berlin, Germany

Salary: EUR 60,000–70,000 yearly

Company

hirify.global is a European e-commerce company combining fashion and technology to create personalized online shopping experiences.

What you will do

• Develop the recommendation engine for the homepage, product pages, and outfit pages using Node.js and TypeScript.
• Serve offline-trained machine learning models, including matrix factorization, brand similarity, and image embeddings, at Black Friday scale.
• Design personalization logic covering feed assembly, fallback chains, deduplication, diversity, and A/B experimentation.
• Build streaming GenAI product features, including a Gemini fashion advisor, with low latency, session state, and token cost control.
• Own reverse-ETL pipelines that move BigQuery model outputs into high-performance data stores.
• Monitor recommendation coverage, track business metrics, and shape the architecture with the Tech Lead.

Requirements

• 3+ years of experience building high-throughput backend services.
• Strong Node.js and TypeScript experience, or the ability to transition quickly from Java, Go, or Kotlin.
• Deep experience with Redis or Valkey data modeling, caching hierarchies, TTLs, invalidation, and binary payloads such as Protobuf or Avro.
• Experience operating APIs at 10k+ requests per second under strict latency SLOs.
• Ability to integrate model scores, embeddings, or LLM features into live backend systems.
• Clear communication skills in English and availability to work in Hamburg or Berlin, Germany.

Nice to have

• Recommendation systems fundamentals, including collaborative filtering, matrix factorization, cold-start handling, and diversity algorithms.
• Streaming GenAI or LLM product experience, including chat UX, prompt caching, or guardrails.
• AWS serverless experience with DynamoDB, SQS/SNS, and OpenSearch k-NN indices.
• Performance profiling and load testing with tools such as clinic.js, flamegraphs, or k6.

Culture & Benefits

• Flat hierarchies, direct communication, pragmatic decisions, and clear ownership.
• Inclusive environment focused on acceptance, inclusion, and diverse perspectives.
• Team lunches, afterwork drinks, company events, and informal opportunities to connect.
• Additional employee benefits are provided through the company benefits program.

Hiring process

• Apply online through the career page.
• The hiring team will follow up after reviewing the application.