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William Da CunhaWD

William Da Cunha

CTO | AI Expert (LLM / RAG / Agents) | B2B SaaS

€900/day
Lille, FR
15+ years

Average response time: 1 hour

Freelancer profile translated to English.
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About William

Do you have a critical technical challenge or want to integrate AI into your business? I can assist you as an on-demand CTO to structure, automate, and accelerate your growth with artificial intelligence.

15+ years of tech experience | 8 years CTO | 2 startups founded (€1.3M revenue)
20+ B2B SaaS, e-commerce, and marketplace startups supported
Expert in production B2B SaaS and AI: LLM, RAG, fine-tuning, intelligent agents (Agentic AI)

The problems you might be facing:
- Unstable infrastructure → repeated incidents, exploding costs (reduced infra costs by 60%, incidents from 1/month to <1/year)
- Inefficient organization → loss of velocity, burnout (productivity +30-50% via AI automation, OKRs, leadership)
- AI lag → competition advancing, missed automation (+80% AI projects in production)
- Short-term growth → hindered by technical debt (backend performance x250)

This is where I step in as an AI-First CTO: I align technology, AI strategy, leadership, and business for automated and scalable growth.

Companies supported:
🚀 B2B SaaS & E-commerce Startups: AI integration, scalable architecture, process automation
🏢 Post-funding Scale-ups: AI transformation, data integration, technical organization
🔧 SME Digital Transformation: Cloud modernization, generative AI adoption
⚡ Companies in technical crisis: Infrastructure recovery, performance optimization

Common missions:
🤖 AI Transformation: LLM implementation, RAG, fine-tuning, intelligent agents
🔍 Technical & AI Audit: Infrastructure assessment, automation potential
⚙️ Architecture & Performance: Scalability optimization, serverless migration
🚀 CTO Leadership: Structuring B2B SaaS tech teams, recruitment, coaching
💼 Transition CTO: Critical phases, technical due diligence

Technologies: Python, TypeScript, Node.js, LangChain, LangGraph, AWS, Serverless, Microservices

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📩 Contact me for a quote.
PS: I'm very responsive!
  • French

    Native or bilingual

  • English

    Fluent

  • Portuguese

    Conversational

  • Spanish

    Conversational

Remote only
Primarily works remotely

Experience

  • MyLegiTech
    Interim CTO
    September 2025 - Today (9 months)
    French leader in CLM (2,000+ clients), in a post-merger context of ImmoSign × Séraphin.legal, with a departing CTO and fragile management ↔ tech trust.

    Tasks
    • Ensure handover with the former CTO and guarantee operational continuity.
    • Audit the architecture of existing products and manage the post-M&A replatforming.
    • Restructure the delivery process and restore the management ↔ tech relationship.

    Actions
    • Structured handover with the outgoing CTO: transfer of critical context, mapping of risks and dependencies.
    • Complete architecture review of ImmoSign & Séraphin.legal products, identifying synergies and technical debt.
    • Management of replatforming to unify the technological base following the merger.
    • Redesign of the delivery process: cadence, rituals, monitoring metrics, business-aligned prioritization.
    • Implementation of automation and AI processes and tools to enhance team productivity.
    • Improvement of operations: monitoring, incident management, customer feedback loop.

    Results
    • +60% predictability in delivery
    • x2 productivity thanks to automation and AI
    • Net improvement in customer satisfaction for operations
    • Restored trust between management and the tech department
  • Marjory
    CTO
    SOFTWARE PUBLISHING
    February 2023 - February 2025 (2 years)
    Paris, France
    A data integration SaaS platform aimed to drastically reduce its operational costs and improve its scalability, while remaining compliant with security standards and GDPR.

    Tasks
    • Define the technological and product strategy to support growth.
    • Lead multidisciplinary technical teams (developers, DevOps, data).
    • Ensure GDPR compliance and overall infrastructure security.

    Actions
    • Implementation of an AI strategy
    • Redesign of the architecture to make it more robust and elastic (cloud optimization, reduction of technical debt).
    • Implementation of DevOps best practices (CI/CD, monitoring, alerting) to stabilize deployments and reduce incidents.
    • Team leadership through a clear roadmap (priorities, sprints) to align tech and product with business objectives.
    • Strengthening security (internal audits, awareness) and formalizing GDPR processes.

    Results
    -50% operational costs, including -60% on infrastructure, representing a reduction of over €13k in the AWS bill
    - Improved productivity (30 to 50% depending on the teams) and organizational predictability (+77%)
    - Significant decrease in production incidents: 1 per month on average down to 1 per year
    - 30% reduction in average incident resolution time
    - Established GDPR compliance and preparation for SOC2 certification
    - Delivery of an AI feature on the product (OpenAI model with fine-tuning)
    - Creation of an internal AI agent with RAG, used to double the productivity of connector teams
    CI/CD Amazon Web Services Artificial Intelligence Cross-functional Team Leadership Product Management
  • BeeForYou
    CTO / Co-founder
    DIGITAL AND IT
    March 2018 - February 2023 (4 years and 11 months)
    Lille, France
    I co-founded BeeForYou, a consulting company specializing in supporting tech startups.

    Tasks
    • Business development
    • Team recruitment and training
    • Fractional CTO services for our clients
    Actions
    • Implementation of adapted organizations (roadmap, roles, methodologies)
    • Automation of processes and CI/CD integration
    • Supporting our clients with their technology choices
    • Development of a scalable offering to maximize impact
    Results
    • €1.3M in revenue generated through a targeted and effective approach
    • 20+ developers trained and operational on complex projects
    • 25+ startups supported

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Education

  • Engineer, Telecommunications, Computer Science, Software Engineering
    Télécom Lille
    2011
    Ingénieur, Télécommunication, Informatique, Génie logiciel

Skill set

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