Senior Backend Engineer

ppPeople used to search on Google. Now they ask ChatGPT, Gemini and Perplexity what to buy and which brand to trust, and soon AI will buy for them. /p pMentionLab shows businesses how AI sees them: what AI engines say about their brand, how they compare to competitors, and which sources shape those answers. We're building the data and intelligence layer for AI Search and agentic commerce. /p pBorn in Brussels and global from day one, we already serve global brands directly and through leading consultancies and agencies. /p pWe're moving fast in one of the biggest shifts in how people discover information, and we're looking for people who want to build incredible things with us. /p h3The Role /h3 pAs a Senior Backend Engineer at MentionLab, you'll be at the heart of our data infrastructure. You'll design and maintain the systems that power our analytics platform
- from ingestion pipelines to the APIs that serve insights to our users. If you love working with analytical databases at scale, building fast and reliable data pipelines, have experience with ClickHouse (OLAP), and want to own meaningful parts of a product from day one
- this role is for you. /p h3What You'll Build /h3 ul liOwn our data architecture, from ingestion pipelines to ClickHouse data models, and make the key technical trade-offs /li liDesign and optimise analytical queries and data models that stay fast as volumes grow /li liBuild and maintain the backend APIs that serve insights to our users and partners /li liKeep our pipelines reliable and performant in production /li liWork mainly in TypeScript and SQL,(with Rust) for performance-critical data processing /li liRaise the engineering bar through code reviews, standards and mentoring /li liWear multiple hats (because startup) /li /ul h3The Stack /h3 ul liTypeScript, SQL,(and Rust); /li liNestJS with MikroORM and Knex on PostgreSQL; /li liClickHouse (OLAP) for analytical workloads; /li liRedis for queue management (BullMQ + custom for high throughput). /li /ul h3What We're Looking For /h3 pTechnical

Requirements:
/p ul li5+ years of software engineering experience /li liStrong, hands-on experience with data modelling, query optimisation, and performance tuning /liliSolid knowledge of TypeScript and SQL /li liComfortable working across both analytical and transactional databases /li liExperience with AI-assisted development tools (Copilot, Cursor, Claude Code, or similar) /li /ul pWhat We Value: /p ul liProactive mindset
- spot issues, propose solutions, don't wait to be told /li liComfortable with code reviews and constructive feedback /li liCare about code quality but know when to ship fast /li /ul pNice to Have: /p ul liExperience with NestJS, PostgreSQL, Redis /li liHosting or infrastructure knowledge (Docker / Kubernetes) /li liPrevious startup experience /li liReact or other frontend experience /li /ul h3You’ll Thrive Here If /h3 pYou enjoy figuring things out and don't need hand-holding. You're comfortable with ambiguity and changing priorities. You like collaborating and sharing what you learn. You're excited about AI and its impact on how people discover information. And you're AI-native
- you don't just build AI products, you build with AI. /p h3How We Work /h3 pLanguages: French required. English working proficiency for documentation and some meetings.

Location:
Belgium-based (Brussels
- Hybrid). Permanent contract (CDI)
- 38h/week. /p h3What

We Offer
/h3 pFair salary package including car/mobility budget and insurance /p pDynamic workplace
- Small, ambitious team /p pA chance to shape the technological direction of the company /p pHigh level of autonomy with guidance when needed
- you're not alone /p pImportant note: we hire people, not roles.
If you're excited about this opportunity but don't check every box, we'd love to hear from you. This is a guide, not a checklist. /p /p