About the role

Design and build ML systems end-to-end
Work closely with founding team on AI architecture
Run experiments with new models and data strategies
Define best practices for AI development
Opportunity to influence product and culture from day one

Skills the posting asks for

Python
Machine Learning
NLP
LLMs

Summarised from the employer’s posting, which is reproduced in full below.

The employer’s full posting

We're helping an early-stage startup build an AI-powered platform, and we're looking for a Senior Machine Learning Engineer (NLP) to help shape the core AI/ML architecture behind it. This is a hands-on, high-impact role: you'll design, build, and deploy ML systems end-to-end, working directly with the founding team to deliver 10x value to our clients. If you love solving open-ended problems with AI and want to shape both the product and the engineering culture from day one, this is for you.

Porto (hybrid — 2x/week in office) + Up to €90k/year

What You'll Be Working On

You'll own ML/AI systems at the heart of the platform — from model development and training through to deployment and monitoring. Day to day, that means building intelligent systems for document processing, web data parsing, classification, search, and entity matching, applying modern LLM techniques to messy, real-world problems.

You'll run experiments with new models, data strategies, and agentic AI approaches, while balancing innovation against production realities like reliability, performance, and safety. Beyond the code, you'll help set the standards — defining best practices and tooling for AI development across the company, and collaborating closely with engineers and founders to keep AI capabilities aligned with what the product actually needs.

What They're Looking For

At least 4 years as a Machine Learning / AI Engineer in product-focused environments
Strong, production-level Python
Hands-on experience building AI/ML systems: LLMs, prompt engineering, fine-tuning, multi-agent systems, conversational AI
A solid grasp of modern ML/AI architectures and tooling
A track record of taking models from experimentation all the way to production
Comfort working across data, ML, and backend systems when the job calls for it
Strong analytical thinking and ease with ambiguous, open-ended problems
Excellent communication and collaboration in a fast-paced environment

Why This Opportunity?

This is a rare chance to own AI at the foundation of a product, not inherit it. You'll work shoulder-to-shoulder with the founders, make architectural decisions that stick, and see your work reach clients quickly. With a competitive salary up to €90k, a hybrid setup in Porto, and real influence over both product and engineering culture, it's built for someone who wants their work to matter from day one.