Senior Software Engineer

Lengow is a leader in intelligent e-commerce solutions that help brands and retailers drive profitable growth across the digital shelf. With powerful feed management, global price monitoring, and robust data capabilities, Lengow’s comprehensive SaaS product suite enables merchants to amplify product visibility online, outrun competition with informed pricing, multiply sales on marketplaces, and monitor brand presence among distributors. Since 2009, Lengow has fueled digital growth for over 3,600 customers across thousands of marketing and sales channels in over 60 countries.

Our Tech Team

The Tech, Data, and Product team comprises 70+ people from diverse backgrounds, working in our offices in Nantes, Paris, and Barcelona. Our products are developed thanks to six autonomous product Teams, each working on a specific business domain. The teams are led by a Product Manager and Engineer manager working with a dedicated small team of developers (from 4 to 8)

Purpose of the job

We are looking for a Senior Software Engineer to design and deliver reliable systems at Lengow, mainly on the backend with some frontend work.

How we work. Our engineers drive their work through AI agents. They use them to investigate problems, clarify requirements and plan, then delegate implementation and validation end to end. Each engineer focuses on design and architecture, defines what success looks like, assesses the evidence and decides what goes to production.

What you will work on. Our main engineering challenge is to scale our SaaS to connect more merchants and more marketplaces. For example, we are moving our batch processing system towards an event-driven architecture: how work is triggered, how services coordinate, and how the system stays reliable throughout the migration.

As delegating to AI agents is mandatory, we provide paid AI development tools, including Claude Code or ChatGPT Pro subscriptions.

What you will do

• Own and deliver changes to production end to end using agents, from investigation and analysis to validation and impact.
• Design and implement AI-oriented features in the product.
• Take part in design decisions on the event-driven migration, challenging and being challenged with evidence.
• Improve our agent harness and engineering loop.
• Share what works and what doesn't with concrete examples, and build on what your teammates share.

Who you are

• 4+ years of software engineering, with strong Python skills (Django, PostgreSQL, Celery, Docker).
• Strong software design and architecture skills, including clean architecture principles, and experience running backend services in production with automated tests and CI/CD.
• You see agents as a way to delegate entire engineering tasks end to end, not just to write tests or autocomplete code, and you have hands-on experience doing it. You can explain what you delegated, what failed and how you validated the result.
• Sound judgement on agent output, permissions and access to sensitive data.
• Good written and spoken English.

It would be great if you have worked on event-driven architectures, asynchronous processing or batch-to-event migrations. Experience with PHP or React is also a plus.

Your examples may come from professional work, open source or personal projects. If you don't tick every box, we still encourage you to apply.

Technical environment:

• Langage : Python, PHP, JS/TS
• Framework : Django, Celery, FastAPI, React
• DB : PostgreSQL, Redis, AWS
• Outils : GitHub, Jira, Datadog, Docker, RabbitMQ

Hiring process:

• Phone call with Alexandre our HR
• Interview with one of our Engineering Manager
• Technical test and restitution with Clément Head of Engineering and members of the tech team.
• Offer letter

We are looking for someone with the following experiences and skills:

Experiences:

• 4+ years of software engineering, with strong Backend skills.
• Experience running backend services in production, with automated tests and CI/CD.
• You see agents as a way to delegate entire engineering tasks end to end, not just to write tests or autocomplete code, and you have hands-on experience doing it. You can explain what you delegated, what failed and how you validated the result.

Skills:

• Python, Django, PostgreSQL, Celery, Docker
• Software design and architecture, including clean architecture principles
• Sound judgement on agent output, permissions and access to sensitive data
• Good written and spoken English

Nice to have:

• Event-driven architectures, asynchronous processing or batch-to-event migrations
• PHP or React

At Lengow, we value diversity in all its forms and are committed to equal opportunities. All applications are considered based on skills and qualifications, including those from candidates with disabilities.

✨ Joining Lengow is also an opportunity to benefit from many advantages :

• Ticket restaurant 8 euros by day
• Malakoff Humanis Private insurance & Prevoyance.
• 3 Remote days per week
• Flexible hours
• Bike mileage allowances or 50% of transportation tickets.
• Remote allowances
• Professional events (Devoxx, Meetup ...) and regular internal cohesion.
• Weekly Happy Break on Thursday Evening at the office with food and beverage
• Syntec forfait jours with RTT - 218 annual working days, ie minimum 9 days off on top of 5 weeks legal paid leave
• Choose your laptop OS. You can work on MacOS, Windows or Linux.