AI Engineer

Why Omnilex?

At Omnilex, we’re on a mission to transform the way lawyers work. Our AI-native platform lets legal professionals enhance their productivity in legal research and automate workflows. We collaborate closely with our clients and iterate at a market-leading pace. In a year, we have gone from an early MVP to a product used daily by thousands of legal professionals at our clients in Switzerland, Germany and Liechtenstein - and are now scaling rapidly across Europe.

We already stand out with handling unique challenges, including our combination of external data, customer-internal data and our own innovative AI-first legal commentaries.

You’ll be joining a young, passionate, and dynamic team of 14, with roots at ETH Zurich.

Your role

Do you love making search actually work well for the user? Are you hands-on with ranking algorithms, query understanding, and excited to ship improvements that users feel the same day? Do you enjoy building pragmatic, low-latency, cost-aware solutions for AI-assisted legal research (where citations, precision, and traceability matter)? If so, we’d love to hear from you.

What you'll do

As an AI Engineer – Legal Search Optimization, you will focus on building and shipping retrieval, reasoning, and context engineering that powers our legal research experience.

• Retrieval & ranking: Implement and iterate domain-specific retrieval and reranking algorithms going beyond the standard ones, including knowledge graphs and custom workflows.
• LLM-powered products: Design and build robust, production-grade LLM systems and chatbots.
• Signals & features: Design scoring features from citations, authority, recency, jurisdiction, section/paragraph structure, and intra-doc anchors.
• Practical considerations: Carefully evaluate decisions like API vs. self-hosted; add batching, early-exit, and caching to control cost/latency.
• Evaluation that guides shipping: Define offline eval sets, run quick ablations, and watch production feedback and dashboards.
• Search infrastructure: Tune indices, analyzers, and embeddings; manage recall/precision trade-offs and de-duplication/near-duplicate suppression.
• Cost & performance: Keep token usage, GPU/CPU time, and indexing costs under control with caching, pre-computation, and fallbacks.
• Collaboration: Work closely with legal experts to turn user pain points into ranking features; document decisions and share clear playbooks.

What you bring

Minimum qualifications

• Strong hands-on experience improving search/retrieval systems (hybrid retrieval, reranking, or query understanding) in production.
• Proven experience in building and deploying LLM-based products from prototyping to production
• Solid algorithms background (data structures, complexity, graph theory, statistics), IR/NLP intuition, and practical SQL skills.
• Proficiency in TypeScript/Node.js (our core stack).
• Experience with one or more of: Azure AI Search, pgvector/PostgreSQL, OpenSearch/Elasticsearch, or similar.
• Familiarity with modern embedding models and cross-encoders for reranking; ability to reason about latency, throughput, and quality trade-offs.
• Ownership mindset, clear communication, and bias for action.
• Proficiency in English;
• Availability full-time. On-site in Zurich at least two days per week (hybrid).

Preferred qualifications

• You have a Swiss work permit or EU/EFTA citizenship.
• Working proficiency in German (many sources are in German and we talk to German-speaking customers).
• Experience with evaluation pipelines (AI as judge, human-in-the-loop labeling, inter-annotator agreement, error analysis) applied pragmatically.
• Practical knowledge of sparse methods (BM25+/BM25L/SPLADE), dense models (e5/BGE/ColBERT-style), and semantic re-ranking.
• Experience deploying/operating small models or services (Docker; basic Kubernetes or serverless is a plus).
• Familiarity with our stack: Azure / NestJS / Next.js.
• Knowledge and experience with legal systems, in particular Switzerland, Germany, USA 🧑‍⚖️

Benefits

• Direct impact: your ranking and retrieval changes immediately improve result quality and user trust.
• Autonomy & ownership: Shape our legal research pipeline, across multi-facetted user intention understanding, dynamic retrieval and reranking
• Team: Work with a sharp, interdisciplinary team at the intersection of AI, search, and law.
• Compensation: CHF 8’000–12’000 per month + ESOP (employee stock options), depending on experience and skills.

We’re excited to hear from candidates who are passionate about making legal search fast, accurate, and trustworthy.