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Nicolas KleinNK

Nicolas Klein

CTO | Critical Systems and AI Agent Architecture

€1,000/day
Paris, FR
15+ years

Average response time: 1 hour

Freelancer profile translated to English.
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About Nicolas

Software architect and CTO with 15 years of experience building high-volume critical systems (fintech, e-health, online betting), I now help companies transition from AI experimentation to production.
My current playground: designing robust and scalable AI agent architectures — systems capable of reasoning, orchestrating, and acting autonomously, integrated into existing systems — applying the same requirements developed for regulated banking and medical platforms: resilience, observability, security, cost control.
I work on software and AI architecture missions for scale-ups and large enterprises: architecture audits and design, POCs on technically complex topics, participation in task forces to resolve structural issues, and supporting teams in upskilling on new AI paradigms.
Two exits > €50M as co-founder CTO. I know what building to last means.
  • French

    Native or bilingual

Can work on-site
Paris (up to 50km)

Experience

  • Pixpay
    Co-founder & CTO
    SOFTWARE PUBLISHING
    January 2019 - Today (7 years and 5 months)
    Île-de-France, France
    Co-founder and Chief Technology Officer of a leading European fintech company, which achieved an exit of over €50 million, operating critical banking infrastructures.

    Definition and management of the technological architecture from the outset: secure and scalable cloud-native infrastructure on AWS, real-time integration of banking and payment systems, and management of high-volume transactional flows.

    The platform now serves over 500,000 clients, with high demands in terms of availability, performance, and resilience.

    Overall responsibility for IT strategy, cybersecurity, and risk management.
    Implementation of DevSecOps standards and structuring of engineering practices in an environment with high operational constraints.
    IT Architecture Full-stack Development Artificial Intelligence (AI) AI Automation
  • MonDocteur
    CTO & co-founder
    December 2013 - December 2018 (5 years)
    Paris Metropolitan Area, France
    Co-founder and Chief Technology Officer of a leading e-health SaaS provider, sold for over €50 million.

    Design and structuring of the technological architecture from the outset, managing up to 3 million medical appointments per month for over 20,000 practitioners.

    Building a highly scalable and secure platform, adapted to the constraints of the medical sector and rapid national growth.

    Structuring of technical teams and management of scaling in a hyper-growth context supported by over €20 million in investment.
  • UNIBET FRANCE
    CTO
    January 2012 - January 2014 (2 years)
    Technological direction of a major international online betting company operating a high-traffic transactional SaaS platform.

    Design and deployment of a real-time architecture built from the ground up, capable of handling massive volumes of financial transactions with minimal latency requirements and 24/7 service continuity.

    Responsibility for the performance, resilience, and scalability of systems in a highly regulated international environment.

    Management and structuring of a technology organization of over 50 engineers (development, infrastructure, production), implementation of architecture standards, and management of strategic roadmaps on an international scale.

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Education

  • Engineer
    Paris
    2001
    Engineer

Skill set

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