AI Engineer — Core AI

Are you looking to have an impact on the daily life of millions of entrepreneurs in France (and tomorrow in Europe)? Are you looking for a work environment that values trust, proactivity, and autonomy? Are our Engineering principles aligned with your vision? Then Pennylane is the right place for you!

Our vision

We aim to become the most beloved financial Operating System of French SMEs and Accounting Firms (and soon, European ones). We help entrepreneurs rid themselves of time-consuming tasks related to accounting and finance while giving them access to the key financial information they need to make the best decisions for their business.

About us

Pennylane is one of the fastest growing Fintechs in France (and soon in Europe!). In 5 years of existence, we've managed to:

• Make ourselves known as a groundbreaking accounting and financial software for small businesses and their accountants
• Raise a total of €400 million, including from Sequoia — the famous Silicon Valley fund that invested early in companies like Google, Facebook, Airbnb, Stripe and Paypal
• Grow from 7 cofounders to 1,000 happy Pennylaners, and earn a place among the greatest companies to work for in France (and remotely), with a 4.6/5 rating on Glassdoor
• Build an international environment with more than 25 nationalities and a strong remote-friendly culture, where 30% of employees already work from all parts of Europe
• Earn the trust of thousands of customers and accounting firms, with outstanding ratings
• Reach more than 1,000,000 small and medium-sized enterprises (SMEs) and over 6,000 accounting firms using Pennylane in France

Why Core AI matters

AI is reshaping how entrepreneurs and accountants work — and a growing share of the traffic to our product will increasingly come from agents, not only from humans. The Core AI team sits at the heart of our AI strategy: while our solution squads (Copilot, Autopilot, AI Studio) build customer-facing AI features, Core AI builds the shared foundations they all rely on, giving Pennylane a durable technical edge — including on cost and sovereignty.

Why this position matters

By joining Core AI as an AI Engineer, you'll play a pivotal role in large projects, bringing your engineering and machine learning expertise to build the agentic intelligence, quality and models that our solution squads rely on.

How you'll contribute

• Build and maintain the agent harness — the core runtime that orchestrates LLM calls, tool use, context construction, memory and guardrails — and make it reliable in production.
• Own the evaluation stack: design eval pipelines, golden datasets, LLM-as-judge and human-eval workflows; track agent performance, regressions and failure modes, and turn production failures into systematic improvements.
• Do prompt and behaviour engineering and retrieval/RAG at scale, defining what "good" looks like for agents completing complex accounting workflows end to end.
• Host and improve our own small models where it creates leverage: serving and inference of open-source LLMs, help fine-tuning and post-training (SFT / DPO / RL), and document-extraction models — for performance, cost and sovereignty.
• Work closely with Product teams and domain experts (accountants) so that fulfilling real user needs stays at the center of what we build.

What you can expect

Within one month:

• You'll learn everything about our company, our teams and our vision during the first onboarding week.
• You'll get familiar with our stack and AI tooling (agent harness, evaluation tooling, model providers, MCP), and deliver a few small contributions that give you a concrete taste of our tools and processes.
• You'll be given time to meet your future stakeholders and gain a deep knowledge of our product and operations.

**Within 3 m