Co-founder CTO (Tech) H/F

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Co-founder & CTO - Build a Company with OSS Ventures (Paris)

At OSS Ventures we're looking for a Co-founder CTO (Tech) to join one of our future ventures.

Full-time · Paris

About OSS Ventures

OSS Ventures is a startup studio and investment firm dedicated to building B2B software companies for operations.

We co-found companies with experienced founders and support them hands-on across:

  • Product

  • Go-to-market

  • Technology

  • Hiring & org design

  • Fundraising

OSS is neither an incubator nor a passive investor.
We work side by side with founders, with a clear execution framework, direct access to an industrial customer network, and a team of operators who have already built and scaled companies.

You can find more context on the team and partners here:
https://www.oss.ventures/about-us

The Role

You are joining as Co-founder & CTO of a new company built with OSS.

Your responsibilities include:

  • Leading the technical strategy and architecture

  • Building and evolving the product foundation

  • Ensuring scalable, secure and maintainable tech delivery

  • Shaping how engineering works in tight early-stage constraints

  • Hiring and mentoring the early technical team

  • Partnering with the CEO on technical and product decisions

  • Supporting fundraising with clear technical narratives

This is a founder role, not a senior engineering position.
You co-create and co-own the company with OSS and your co-founder.

What Makes This Setup Different

You are not starting alone.

With OSS, founders benefit from:

  • Direct access to an industrial and operational network

    • Real customers

    • Fast feedback loops

    • Early use cases that shape the product

  • A hands-on operating team

    • Tech, product, revenue, people and fundraising

  • Reusable execution foundations

    • Proven product frameworks

    • Security and scalability baselines

    • Tech playbooks and toolkits

  • Founder matchmaking

    • OSS actively pairs complementary CEO and CTO profiles

  • Credibility from day one

    • With customers

    • With early-stage investors

The objective is to reduce early execution risk and help founders deliver something real, usable and valuable fast.

What Success Looks Like (9–12 months)

Together, the goal is to build a company that is ready to scale, with:

  • 5–10 paying customers

  • ~500k+ ARR or equivalent signed revenue

  • A product in production, used by real users

  • Clear technical stability and early scale foundations

  • A repeatable go-to-market motion

  • A technical team and structure ready for growth

After the Program

OSS remains a long-term partner.

This typically includes:

  • Board-level involvement

  • Ad hoc strategic support

  • The ability to temporarily allocate OSS team members for focused deep work with founders
    (e.g. revenue architecture, product pivot, org design, specific technical challenges)

The level of involvement naturally evolves as the company scales.

Founder Profile

This role is designed for experienced technical builders who are ready to found a company.

CTO requirements

  • 5+ years of software development experience

    • Strong production experience

    • Ownership of significant technical decisions

  • 5+ years of team leadership experience

    • Managing engineers and shaping team effectiveness

    • Hiring, mentoring and structuring early technical teams

  • Demonstrated ability to:

    • Build in ambiguous, early-stage contexts

    • Make trade-offs under constraints

    • Align technical direction with business needs

The OSS Deal

  • Unpaid until first fundraising

    • Typically 12 to 18 months

  • Equity split

    • 75% founders

    • 25% OSS Ventures

  • Paris-based during the 9-month program

  • Full commitment expected

This framework is explicit and designed for founders who are ready to fully commit to building a company from scratch.

Selection Process

The process is designed to ensure clarity and alignment on both sides.

  1. Alignment & Readiness Call (30 min)
    Clarify the framework, expectations and constraints.

  2. Deep Interview + Technical Product Business Case with OSS Partner (1.5h)
    Focus on execution depth, architectural thinking, product sense, prioritization and leadership.

  3. Final Business Case with OSS Partnership (2h)

    • Presentation of a product/tech session

    • Discussion with partners

    • Dedicated time to ask all remaining questions about the collaboration

  4. Discovery & Choice of Space (up to 1 week)
    Time for reflection before commitment.

How to Apply

Apply if — and only if — this setup aligns with your experience, constraints and ambition.

Your application should include:

  • Your CV

  • A short explanation of:

    • Why you want to build with OSS

    • What you have built or led before

    • What type of company you want to create

Before Applying

We kindly advise you to think twice before applying if:

  • You are looking for a salaried position or short-term security

  • You are not in a position to commit full-time for 12–18 months without salary

  • You prefer a loosely structured environment or minimal accountability

  • You are uncomfortable making decisions with incomplete information

  • You are not ready to take full ownership of outcomes as a founder

This role is designed for founders who are intentionally choosing a demanding path, with clear trade-offs and long-term ambition.

Apply now

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