Senior AI Evals Engineer (AI Quality & Safety) - Libra-Legal AI Assistant (m/w/d)
About Us
As an Evals Engineer (m/w/d)
Optimizing a system against a target is newly automatable: LLM optimizers
GEPA
now propose and test the candidates themselves. Nobody has to invent the experiments any more, and the system will improve in whatever direction the evals point, whether or not that's where you meant to go. That makes defining what good means the highest-leverage work we do, and it has to be done task by task, from scratch, for a legal AI platform at European scale. You'll work in a lean, agile environment with AI Engineers, Legal Engineers and Product, based at the vibrant Merantix AI Campus in Berlin, surrounded by a community of AI innovators.
What you'll do
- Build and own the eval platform: datasets, judges, harnesses, regression gates, cost and quality in one view, on
Python
FastAPI
Langfuse
. Make it self-service, so AI Engineers can evaluate and tune their own features without going through you, and eval-driven development becomes the most effective path rather than a tax.
- Map the quality landscape: good means something different for research, drafting, summarisation and retrieval, and again per jurisdiction. Work out what a defensible measure looks like for each, going first on the ones nobody has evaluated before and then making them repeatable without you.
- Design the rubrics and set the standard for LLM-as-judge: turn Legal Engineers' and subject-matter experts' judgment into version-controlled criteria, keep judges recalibrated as models and jurisdictions change, and make authoring cheap enough to do at volume on privileged material.
- Deep-dive results and traces until you can say why something failed, then find the lever that moves it and automate the fix.
- Unhobble the optimizer: instrument the app so prompts, hyperparameters and harness architecture become levers a search can safely pull, then run automated optimization (GEPA, DSPy) over them against a fitness function you trust, widening that surface as you go.
- Make cheaper models win: treat quality per euro as a first-class metric, instrumented per call, and find the configuration where a smaller model matches or beats an expensive one.
- Own guardrails: ungrounded advice, invented or misattributed citations, jurisdiction and language leakage, prompt injection from ingested documents. Design them, red-team them, prove they hold.
What you'll bring
Education
- Bachelor's degree or equivalent in a relevant technical field (e.g. Computer Science, Software Engineering, Statistics, Data Science); advanced degree is a plus.
Experience
Minimum 5 years
at least 1 building LLM-powered products in production
.
- Strong
Python
FastAPI
, modern tooling, and the data stack (pandas, numpy, notebooks), because much of this job is analysis.
- Hands-on experience
designing evaluations
: datasets, rubrics, LLM-as-judge, benchmarking, human labelling.
- Solid security and data-privacy practice. You'll handle traces, documents and datasets derived from privileged legal material.
- AI coding agents (Claude Code, Codex, Cursor) in your daily workflow.
- Genuine interest in the legal domain.
- Bonus: automated prompt or pipeline optimization (GEPA, DSPy or similar), and a broader data science toolkit, e.g. embedding clustering to check dataset coverage.
Skills
A strong engineer who hasn't hand-written code in months
You think in systems and expect them to be gamed
Hard to fool by a single number
You get expertise out of people who have no time to give you any
Runs on macro-management
Excellent communication in English
.
What we offer:
- Permanent employment
from day one. •
Remote work & flexibility
Work abroad flexibly
Rest & time off
Show your commitment
Support for development
Mobility on the go
Company pension scheme.
Well equipped for working from home
Modern on-site working
A great start
Our Interview Practices
Not included in the source posting: what you'll do, benefits.
Skills
Who can apply
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