Senior Full-Stack Developer AI Engineer Data Scientist M W D

Job Description Location: Berlin / Remote (DACH time zone)

Employment Type: Full-time, permanent

Start Date: Immediate

Language: Native-level English proficiency (C1-C2 level, German a bonus)

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About Us sandan AI is a Berlin-based AI-native startup serving enterprise customers across the DACH region. We are shaping what marketing looks like in an agentic economy — and building the platform on which this new generation of marketing workflows runs.

Our ambition is to build software the way software should be built in 2026: agentic, iterative, and with AI as an integral part of the engineering workflow.

How We Work We use code harnesses such as Claude Code and Codex not as gimmicks, but as a core part of our development process. Our engineers work daily with agentic coding workflows — from architecture sketches and implementation to refactoring and testing.

People joining us either already work productively with these tools or bring the clear motivation to learn and master them quickly and deeply.

Tasks

• Develop and maintain our full-stack applications within the modern JavaScript/TypeScript ecosystem
• Design and implement scalable backend services using Node.js and Nest.js
• Build high-performance frontend solutions with React.js and Next.js
• Design and optimize relational databases (PostgreSQL, MySQL, MS SQL)
• Containerize and orchestrate services using Docker and Kubernetes
• Develop and integrate REST APIs
• Build and operate data pipelines, feature stores, and ML workflows for our agentic systems
• Develop, train, and evaluate machine learning models for marketing use cases (attribution, targeting, forecasting, anomaly detection)
• Implement Retrieval-Augmented Generation (RAG) pipelines (embeddings, vector stores, re-ranking)
• Set up and maintain LLM evaluation frameworks, prompt optimization workflows, and systematic quality benchmarks
• Apply code harnesses (especially Claude Code and Codex) throughout the daily development process — from planning and implementation to code review
• Collaborate closely with the founding team on the product architecture of agentic systems

Requirements Core Technical Competencies (Engineering)

• Several years of professional experience in full-stack development
• Strong knowledge of TypeScript and JavaScript
• Confident working with React.js, Next.js, Node.js, and Nest.js
• Experience with relational databases (PostgreSQL, MySQL, MS SQL)
• Hands-on experience with container technologies (Docker, Kubernetes)
• Familiarity with REST API design and Git workflows

Data Science & Machine Learning

• Solid Python skills, including common data/ML stacks (pandas, NumPy, scikit-learn, PyTorch, or TensorFlow)
• Experience across the end-to-end lifecycle of ML models: data preparation, feature engineering, training, validation, deployment, and monitoring
• Strong understanding of statistical fundamentals (hypothesis testing, regression, classification, time series)
• Experience with modern LLM workflows: prompt engineering, RAG, embeddings, vector databases (e.g. Pinecone, Weaviate, pgvector)
• Hands-on experience in model evaluation: metrics, benchmarks, A/B testing, and systematic evaluation frameworks
• Experience with notebook-based exploration environments (Jupyter, Colab) and transitioning them into production-ready pipelines
• Familiarity with MLOps tools (e.g. MLflow, Weights & Biases, DVC) is a plus

Code Harnesses

• Experience with Claude Code and/or Codex is highly appreciated — otherwise, a strong willingness to actively learn and adopt these tools

Personal Qualifications

• Excellent German (C2) and English skills (minimum C1)
• Genuine interest in generative AI and agentic systems
• Builder mentality: you deliver production-grade software, not just prototypes
• Analyt