Senior Software Engineer

Legal AI is only as good as the knowledge behind it. At Lefebvre Sdu, we've been building that knowledge for over 200 years. Day in, day out. Law by law. Word by word. As the Dutch heart of Lefebvre Group, the European leader in legal and tax knowledge, we're also developing our own platform: GenIA-L, where lawyers and tax advisors don't just get an answer, but an answer they're willing to attach their name to. More than 75,000 professionals use it daily, generating over 100 million euros in ARR across Europe. We're looking for a Senior Software Engineer to help build that.

HOW YOU'LL MOVE US FORWARD

We're bringing separate knowledge portals together into one platform, with AI as the primary way users interact with our platform. We're building GenIA-L: an agentic AI solution that understands and answers legal questions based on our own, trusted content. With you on board, the team will be able to take end-to-end ownership of its own components. In practice, the role is backend-first: you'll take ownership of business-critical Node.js services around authentication, authorization, and user management, along with components like PDF export and chat delivery via Redis. Ownership in this role at Lefebvre Sdu means actively driving continuous improvement, stabilization, and simplification of these systems: so you won't just be keeping the lights on. Frontend work will also come up, so a solid frontend level is desired. The product is under active development, so what you build and improve now will determine how stable and scalable this platform is a year from now.

WHAT WE'RE LOOKING FOR

Technical depth is a non-negotiable. You have extensive experience with TypeScript and , preferably with authentication and authorization systems in production environments, as this is the most important part of the role. You're well-versed in OAuth 2.0 / OIDC flows and aren't afraid to untangle complex system integrations around permissions and roles. You take ownership: you're comfortable with stakeholder management and proactively drive improvement, simplification, stabilization, and documentation. Frontend doesn't need to be your greatest strength, but you should be good enough at it to pick it up from time to time.

• TypeScript / Node.js and related frameworks (e.g., NestJS, Koa)

• Authentication and authorization (OAuth 2.0 / OIDC)

• GraphQL / Apollo

• Relational databases (Postgres, SQLite, MariaDB) and Firebase

• Redis

• Docker, CI/CD (GitHub Actions)

• AWS / Kubernetes / Helm is a strong plus

• Familiarity with ORMs (e.g., Prisma, MikroORM)

• Familiarity with React / Next.js

WHAT YOU'RE SIGNING UP FOR

At Lefebvre Sdu, you'll work in an organization that's in the middle of a transformation and takes the public market seriously. That's the direction, and we're making the journey together. You'll get the mandate, the space, and the colleagues to make it happen.

You'll join a team with a Product Owner, three frontend developers, a UX designer, and a Scrum Master who also works across multiple teams. You'll have room to shape your role and help determine how we work, with a clear shared goal: building the AI-first platform. You'll bring the backend experience the team needs to take real end-to-end ownership, and you'll report to the Lead Frontend Developer. You'll take part in the team's regular scrum rituals (dailies, refinements, retros, planning) and have one-on-ones with your manager. Through the team, you'll also be an important point of contact for application administrators and customer support who need technical assistance, so you should enjoy breaking down technical problems and communicating about them with less technical colleagues.

• A place where you have influence from day one: on the approach, the processes, and the direction.

• Colleagues who deliberately chose Lefebvre Sdu over big tech jobs because here, they're building something that doesn't exist yet.

• Salary between €5,500 and €6,450 per month, based on a 36-hour week, since that's full-time for us.

• A bonus tied to company performance: a fixed year-end bonus of 4% and profit sharing of up to 6%.

• 23 vacation days and a personal choice budget of 12%, of which 8% is holiday pay and 4% is freely allocable. Want more vacation? Just buy it.

• A solid pension plan through PGB, including supplementary partner insurance.

• Collective insurance plans.

• A travel allowance of €0.25 per kilometer or a public transport reimbursement, plus an attractive bike plan. For employees with a commute of less than 10 km or more than 60 km, we have an adjusted arrangement.

• Two days a week in the office in The Hague, within walking distance of Voorburg station. The rest of the week, wherever you work best.

• Room to grow: in your craft, in your role, in the organization.

WANT TO KNOW MORE?

We'd love to tell you all about the team and the role. Send us your CV and you'll hear from us within a few business days. Have a few questions first? Message or call Elize at 0641186590.

A reference check and a VOG (certificate of good behaviour) are part of the selection process.