Senior Data Engineer (Node/TS)

About MentionLab

People 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.

Hit Apply below to send your application for consideration Ensure that your CV is up to date, and that you have read the job specs first.

MentionLab 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.

Born in Brussels and global from day one, we already serve leading brands directly and through major consultancies and agencies.

We'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.

The Role

As a Senior Data Engineer at MentionLab, you'll own the data layer at the heart of our product. You'll design and run the pipelines that turn raw AI answers into reliable, structured data. You'll also build the ClickHouse models that power our analytics platform and partner deliveries. Our pipelines are built in Node.js and TypeScript, so this role suits a data engineer with strong software engineering skills. If you love analytical databases at scale, care deeply about data quality, and want to own meaningful parts of a product from day one, this role is for you.

What You'll Build

• Own our data architecture end to end: ingestion, transformation, storage and delivery
• Build and scale the pipelines that process what AI engines say across markets, languages and models
• Design ClickHouse data models and queries that stay fast as volumes grow
• Guarantee data quality through validation, deduplication, monitoring and backfills
• Run high-throughput, queue-based processing reliably in production
• Work mainly in TypeScript and SQL, with Rust for performance-critical processing
• Raise the engineering bar through code reviews, standards and mentoring

The Stack

• TypeScript (Node.js) and SQL, with some Rust;
• NestJS with MikroORM and Knex on PostgreSQL;
• ClickHouse for analytical workloads;
• Redis for queue management (BullMQ + custom tooling for high throughput).

What We're Looking For

Technical Requirements:

• 5+ years of engineering experience, including building and running production data pipelines
• Strong, hands-on experience with data modelling, query optimisation and performance tuning on an analytical database (ClickHouse strongly preferred)
• Solid Node.js/TypeScript skills: our pipelines are written in TypeScript, not Python
• Advanced SQL
• Experience with queue-based or event-driven processing at scale (retries, idempotency, backpressure)
• Comfortable working across both analytical and transactional databases
• Experience with AI-assisted development tools (Copilot, Cursor, Claude Code, or similar)

What We Value:

• Proactive mindset: spot issues, propose solutions, don't wait to be told
• Comfortable with code reviews and constructive feedback
• Care about data quality and code quality, but know when to ship fast

Nice to Have:

• Rust experience, or strong interest in picking it up
• Experience with NestJS, PostgreSQL, Redis/BullMQ
• Processing unstructured or multilingual text data (e.g. LLM outputs)
• Delivering data to external consumers (APIs, exports, data feeds)
• Infrastructure knowledge (Docker / Kubernetes, observability)
• Previous startup experience

You'll Thrive Here If

You 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.

How We Work

Languages: French required. English working proficiency for documentation and some meetings. Location: Belgium-based (Brussels - hybrid). Permanent contract (CDI) - 38h/week.

What We Offer

Fair salary package including car/mobility budget and insurance

Small, ambitious team

A chance to shape the technical direction of the company

High level of autonomy with guidance when needed: you're not alone!

→ You'll hear back from us fast, positive or negative. We won't ghost you.

Important note: we hire people, not roles. xqknzec 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.