Full Stack Engineer

MestrIA is a service platform providing end-to-end document intelligence solutions tailored for legal and financial teams across Europe—including law firms, banks, real estate servicers, debt recovery specialists, and insurers, insurance companies, transportation industry..

While generic AI tools struggle with complex, jurisdiction-specific documentation, MestrIA delivers complete, end-to-end workflows: automating data extraction from judicial and financial files, accelerating due diligence, and delivering confidence-scored, audit-ready precision.

Backed by EU funding and based in Spain, our platform operates on GDPR-compliant, EU-based infrastructure aligned with the EU AI Act and is actively expanding across Europe with live production deployments.

The Role

As an early-stage Senior Full-Stack Product Engineer, you will shape both our core end-to-end service platform and our engineering foundations from day one. Working directly with the founders and cross-functional teams, you’ll translate complex legal and financial workflows into secure, scalable, and maintainable software.

What you’ll do daily:

End-to-End Product Engineering:Build responsive front-end interfaces, scalable APIs, database workflows, and real-time processing status pipelines that deliver seamless client solutions.

AI Integration: Connect OCR, LLMs, and document processing pipelines with a focus on asynchronous workers, retries, and structured output validation.

Architecture & Security:Optimize PostgreSQL models, AWS infrastructure, CI/CD, and monitoring with privacy-by-design principles (GDPR / EU data residency).

What We’re Looking For

Core Tech Stack:

Backend:Python (FastAPI) and/or Node.js; experience building asynchronous jobs & RESTful APIs.

Frontend:TypeScript, React, Next.js, HTML, CSS.

Data:PostgreSQL (relational modeling, migrations, performance tuning).

Cloud & DevOps:AWS (ECS/Fargate, App Runner, S3, CDK/IaC), Docker, CI/CD, and production monitoring.

Requirements & Mindset:

System Design:Proven experience shipping secure, end-to-end SaaS products and client-facing platforms.

Integrations:Skilled in integrating 3rd-party APIs, AI services, file upload flows, and background processing.

Compliance & Security:Awareness of GDPR, EU data-residency requirements, and secure handling of sensitive data.

Startup Mindset:Ownership mentality, strong communication skills, and comfort working closely with founders in a fast-paced environment.

Languages:Professional fluency in English. Spanish or another EU language is a plus.

Background:Bachelor’s degree in CS/Engineering (or equivalent hands-on experience / final-year students with strong production work).

What We Offer

Compensation:Competitive salary package alongside equity / share options.

Impact:High ownership in an early-stage, fast-growing startup backed by EU funding.

Flexibility:Hybrid working model based in Madrid, A Coruña, or Barcelona with work-from-home flexibility.

Cutting-Edge Stack:Hands-on experience scaling production LLM, OCR, and AI document processing platforms for enterprise clients.