⚡ Lead Engineer — Fintech / Payments

🏢 The Company

A French fintech company. Over 100,000 active users, a partnership with a licensed payment institution, and a funding round in the works.

Today, most of the development work is handled by external vendors. Tomorrow, it will be handled by an in-house team that you'll help build.

🎯 The Role

Lead in-house engineer. No CTO above you: you're in charge of technical matters. The team is small, and the role is hands-on.

• Coding: That's the core of the job, every day
• Maintain the technical relationship: engage in near-daily communication with the technical director of the partner payment institution, and attend partner and regulatory meetings alongside the founder
• Keeping the big picture in mind: with this product, a side effect isn't paid for in technical debt but in euros
• Building the team: planned hires starting in the first year, with your input on the team's composition

⚠️ What You Need to Know Before Reading On

This isn't your typical software. It involves cash flows. A mistake doesn't just result in a dissatisfied customer—it results in a net loss, potentially in the five-figure range.

Several engineers who have worked at well-known scale-ups have described this environment as more demanding than anything they had experienced elsewhere. The founder prefers to make this clear from the start rather than let them find out three months down the line.

🔨 Technical Challenges

• An in-house payment engine: Following the overhaul, all business rules are now managed on the product side and are no longer delegated to the banking partner
• Complex allocation rules: multiple allocations on a single card, priority order among them, the option for the user to add additional funds, and a reason for rejection that must remain understandable to the end customer
• Load: up to one payment per second during peak season. One minute of downtime means 60 lost payments and an immediate support ticket.
• Security: regular audits, recurring intrusion attempts, regulatory challenges related to payment status

🧑‍💻 The stack

• Backend: NestJS, TypeScript
• Frontend: React, Next.js
• Data: PostgreSQL, MongoDB, RabbitMQ
• Infrastructure: Kubernetes, Terraform
• Mobile: Flutter
• AI: It's largely automated; knowing how to manage it without letting it generate just anything is part of the job

🎯 Ideal Candidate Profile

• An experienced engineer with a high level of autonomy, comfortable getting to the heart of the business
• Payment / PSP: Real-world experience is a major asset. If you don't have that, a strong interest in infrastructure and security, and a desire to quickly learn the business
• Professional curiosity: understanding the rules, not just implementing them. This is the most distinguishing factor for this position.
• Interpersonal skills: You will interact with technical management teams at partner companies and regulatory contacts
• Bonus: a DevOps culture. Here, if something goes wrong, the payment doesn't go through

🏢 The Work Environment

• Daily at 9 a.m., team meets on site
• An intense ramp-up phase
• Direct, daily contact with the founder, with no middlemen

🛑 This job isn't for you if...

• Are you looking for a fully remote position or a comfortable work-life balance?
• Do you want a management role or a role that involves remotely overseeing the code?
• You need a frame that's already been hung: here, you're the one who hangs it

✅ This job is for you if...

• Critical systems involving real money attract you more than they scare you
• You want to stay focused on the technical side while taking on responsibility
• Do you prefer a straightforward work environment, without cumbersome processes or internal politics?

📌 Prerequisites

• Fluency in French: daily communication in French with the founder, internal teams, and partners and regulatory contacts
• Valid authorization to work in France, with no action required on the part of the employer
• Based in the Île-de-France region: on-site work in Paris with a maximum of one fixed day of remote work. Applications requiring full remote work or relocation will not be considered.