Senior AI Software Engineer

Fakto; Neuilly-sur-Seine; On-site; EUR 110,000 - 150,000; Full time

Benefits offered by this job

Meaningful equity

Small senior team

Office near Neuilly Lab

Best tools and stack

Job summary

Fakto is building a Cost Intelligence platform in Paris, focused on enterprise spend and AI-powered agents. You will be among the first engineers, co-owning tech and product strategy, and shaping a scalable architecture with the CTO present in the code.

The role emphasizes hands-on work across back-end, infra, and AI workflows, with strong ownership culture and fast iteration on client problems. The office is in Neuilly-sur-Seine, offering meaningful equity and a small senior team.

Qualifications

• Strong in back-end and DevOps with hands-on experience in Docker, Kubernetes, CI/CD, and production-ready systems.
• Comfortable shipping code that uses LLMs and treating AI as a core value, not a side project.

Responsibilities

• Co-owning the technical and product strategy, deciding what to build and standardize for long-term moat.
• Transform client signals into product features by addressing real-world contract and billing problems.
• Build enterprise-grade agents that read documents, reason over contracts and invoices, and integrate with client systems.
• Keep at the frontier of AI with models, tools, evals, and production-ready infrastructure.
• Be adaptable as the role evolves with quarterly adjustments and client needs.

Skills

Back-end

DevOps

Docker

Kubernetes

CI/CD

Observability

LLMs

Ownership

Team fit

Tools

React

Job description

Large companies spend billions with their suppliers, yet few truly see or control that spend. Fakto is building the Cost Intelligence platform for how companies spend: AI agents that understand every supplier relationship, enforce what was agreed, and increasingly help decide what to buy, from whom and at what price. We start where the money leaks today, in the gap between what’s negotiated and what’s actually paid.

We’re a fast-growing team in Paris, and we care a lot about building a healthy, ambitious, international culture.

What you’ll do

You’re among the first engineering hires, closer to a founder than a senior IC dropping into a defined role. A year from now, parts of this section will look obsolete, and you will have helped rewrite them.

What we can tell you is what you’ll be responsible for:

• Co‑owning the technical and product strategy. What we build, what we don’t, what we standardise vs. keep bespoke, where the moat actually is, what the architecture looks like in 18 months.
• Turning client signal into product. You’ll sit close to the problems clients hand us: messy contracts, opaque billing, edge cases nobody warned us about. Spot the pattern, propose the abstraction, ship the thing that makes the next ten clients easier.
• Building agents that do real enterprise work. A growing share of what Fakto ships is agentic: systems that read enterprise documents, reason across contracts and invoices, surface findings and increasingly act on them inside our clients’ systems.
• Staying at the frontier of AI. Models, tools, agent frameworks, evals: the field moves weekly. We expect you to keep up and bring ideas forward, while keeping focus on the customer needs and not on the hype.
• Whatever else it takes. Some weeks that’s hardening something before a client demo. Some weeks it’s a clean‑sheet prototype on a new use‑case. At our pace, the job rewrites itself every quarter, and you help write it.

You won’t do any of this alone. All three founders are deeply technical and the CTO will be in the code with you.

Why this role, right now

• Join a deeply ambitious team. We’re backed by Tier 1 investors (the funds behind Pigment, Revolut and Ramp) and already have LLM‑based systems running for enterprise clients.
• The technical surface is genuinely hard. Reconciling structured and unstructured financial and operational data, then building agents on top of it: modeling messy documents, building an AI pipeline that measurably improves over time and shipping it on production‑grade infrastructure for Fortune‑500 buyers. It is not a wrapper on an API.
• Large scope, large upside. You’ll report directly to the CTO and have a real say in architecture, hiring bar, engineering culture and product roadmap. If you want to start a company one day, there’s no better seat to learn from.
• A culture of ownership, not face time. We don’t normalise working outside office hours. We also don’t pretend client deadlines aren’t real. If the work is done, leave early. If a client demo is tomorrow and something’s broken, we expect you to care.

What we’re looking for in you

The non‑negotiables

• You’re strong in back‑end, and you’ve touched DevOps / SRE / infra seriously enough to have opinions about Docker, Kubernetes, CI/CD, observability and what “production‑ready” actually means.
• You’re comfortable shipping code that uses LLMs, or you’re hungry to be. What we care about is that you see AI as the reason to be here, not a price to pay.
• You have ownership instincts. If something’s late and the client demo is tomorrow, you don’t need to be told.
• You fit the team. Healthy disagreement, low ego, kindness and the ability to hold a high bar without making everyone miserable.

Strong bonus

• You have 5+ years of professional engineering experience.
• You’ve shipped something where you owned the model, the data layer and the way it was exposed to the user.
• You’ve worked in a true startup environment where the line between back‑end, infra and “whatever needs doing” is blurry.
• You’ve done some front‑end (React or otherwise) and don’t run away from it - but you don’t want to live there full‑time.

We care less about

• Having worked in an AI role. Some of the best people for this role haven’t built agents yet: they just want.
• A perfect match on all five buckets (back‑end, infra, security, data, front‑end). One deep strength + two genuine curiosities is plenty.

What we offer

• Meaningful early‑employee equity.
• A small, senior team. You’ll help build what takes us to Series A and beyond.
• An office we actually like coming to at Neuilly Lab, one minute on foot from Les Sablons metro (Line 1).
• The best tools. Latest models, best stack, a MacBook Pro, no procurement battles to use Claude or anything else that makes you faster.

Hiring process

We’ve designed this to be fast, respectful of your time and high signal on both sides.

• 30‑minute intro call with Charles (CTO).
• Time‑constrained technical exercise. Delivered within ~two hours of receiving it. Done from home.
• Technical debrief call with Charles. We care less about whether the code is perfect and much more about how you reasoned through your choices and what you ran out of time for.
• Founders’ fit conversations (in person). You meet the other two co‑founders, Benjamin and Nicolas.
• Offer & references.

If at any point we don’t think it’s a fit, we’ll tell you quickly and honestly. We expect the same in return.