Full Stack Engineer

Company Description:

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.