ML Research Engineer

White Circle; Paris, France; Hybride; EUR 80 000 - 140 000; Plein temps

Avantages offerts par ce poste

Equity

Flexible time off

Office in central Paris

Relocation support to Paris

Résumé du poste

White Circle is seeking several ML Engineers to train, post-train, and evaluate the LLMs at the core of our platform. You will work on petabyte-scale datasets, building scalable pipelines, and applying labeling, alignment, and evaluation methods to improve model safety and performance.

Ideal candidates have strong Python/SQL, NLP/ML experience with real-world text, and comfort with distributed processing at scale.

Qualifications

• Strong Python + SQL with an engineering mindset.
• Applied NLP/ML experience on real-world text.
• Experience with large-scale data pipelines and distributed systems.

Responsabilités

• Turn petabytes of unstructured text into a structured, explorable view.
• Build scalable representation pipelines, embeddings, indexing, and retrieval.
• Use LLMs pragmatically for labeling, summarization, and diagnostics.
• Deliver insights that drive product and operational decisions.
• Ship self-serve analytics with datasets and lightweight dashboards.
• Collaborate with engineering and research to align with production constraints.

Connaissances

Python

SQL

NLP/ML

Embeddings

Distributed processing

Cost/latency tradeoffs

Outils

HuggingFace

PyTorch

Description du poste

TLDR: We are looking for several ML Engineers to train, post-train, and evaluate the LLMs at the core of our platform. This is hands-on modern model training work: large-scale data pipelines, SFT/RLHF/DPO-style alignment, reward models, distributed multi-GPU training, and evaluation.

About us

White Circle https://whitecircle.ai/ is an AI Safety company building the safety, reliability, and optimization layer for AI systems. At the core of our platform are policies - simple natural-language rules that define what an AI model should and shouldn't do. We automatically test, enforce, and continuously improve these policies at scale.

• We've raised $11M from top funds, founders, and senior leaders at OpenAI, Anthropic, HuggingFace, Mistral, DeepMind, Datadog, Sentry, and others
• We process over 100M+ API calls every month
• We fine-tune and train our own LLMs so they run faster and cheaper than any open or proprietary model

We're a small, highly focused team. If you want to work deeply on hard problems, see your work ship to production quickly, and influence how AI safety is actually built - you're the one we need.

What you'll do

• Turn petabytes of unstructured text into a structured, explorable view (topics, clusters, segments, trends, anomalies): iterate from "unknown unknowns" to stable definitions we can track.
• Build scalable representation pipelines: sampling strategies, preprocessing/normalization, embeddings at scale, indexing, and retrieval to make the corpus searchable and analyzable.
• Use LLMs pragmatically: labeling/classification, weak supervision, data enrichment, summarization, and automated diagnostics of inbound volumes (with cost/quality controls).
• Deliver insights that change decisions: translate findings into product and operational actions (what data we have, what's missing, where quality breaks, what to prioritize next).
• Ship self-serve analytics: datasets, data models, and lightweight tools/dashboards so the team can explore and answer questions without ad-hoc requests.
• Partner closely with engineering/research: align pipelines with production constraints (latency/cost/privacy), and integrate outputs into workflows.

You'll fit right in if you

• Have strong Python + SQL with an engineering mindset: you can build reliable pipelines, not just notebooks.
• Have solid applied NLP/ML experience on real-world text: embeddings, clustering, topic modeling, semantic search, classification; you understand failure modes and how to debug them.
• Are comfortable at scale: distributed processing, large-scale storage-querying, and performance-cost tradeoffs.
• Know how to evaluate fuzzy problems: offline/online metrics, human-in-the-loop labeling, inter-annotator agreement, drift monitoring, and reproducibility.
• Have prior work with safety/moderation datasets, policy/rule systems, or high-volume logging/observability

A big plus

• A public builder footprint: open-source models, datasets, or training frameworks on HuggingFace/GitHub, benchmarks, papers (workshop or main conference), or technical posts with real usage
• Experience training models at a frontier or near-frontier lab, or leading open-source model releases with documented adoption
• Experience with RL methods for LLMs beyond standard RLHF: online RL, GRPO-style methods, or novel alignment approaches
• Experience with moderation, safety, or classification models at scale
• Multilingual model training experience

Compensation & benefits

• Competitive compensation, including equity
• Flexible time off
• Office in central London/Paris with flexible hybrid setup
• Relocation support if you're moving to Paris, available after your probationary period
• Premium private health insurance
• Mental health support, including coverage for therapy when you need it
• Lunch and dinner covered when you work from the office
• Learning and development support for courses, conferences, and opportunities to grow your skills
• All the hardware, subscriptions, tools, and services you need
• Team off-sites twice a year: we've recently been to the Alps, Saint-Tropez, and Marbella

Process

1. Intro call with Talent Team
2. Test assignment
3. Technical interview with Head of Applied Research
4. Final conversation with our CEO