CTO as a Service
Your CTO as a Service. Technical leadership without hiring a full-time CTO.
Collybrix provides the strategic technical leadership your startup needs at the most critical stages: pre-seed and seed. Technical roadmap, scalable architecture, team leadership and investor readiness. Minimum commitment of 3 months, cancellable with 30 days' notice.
What is a CTO as a Service?
CTO as a Service A (also called Fractional CTO or External CTO) is an experienced technology director who works with your startup part-time, bringing the same strategic vision as a full-time CTO but at a fraction of the cost.
Hiring a senior full-time CTO costs between €80,000 and €150,000 per year in gross salary, not counting stock options, social security and benefits. For most startups in the pre-seed or seed stage, that cost is unaffordable when capital must go toward product and customer acquisition.
With the Collybrix CTO as a Service model, you get high-level technical leadership, with 15+ years of experience building scalable systems and leading technical teams at pre-seed and seed stage startups, with a level of dedication that adapts to your startup's stage.
Our external CTOs don't just write code: they define the technical strategy, lead the development team, make architecture decisions and prepare you for critical moments: the MVP launch, the investment round and post-seed growth.
What the CTO as a Service includes
Business-aligned technical roadmap
We prioritize technical decisions that maximize impact on business metrics: conversion, retention, time-to-market.
Team leadership and mentoring
We lead and mentor your development team to work with proven methodologies, faster and with fewer bugs.
Scalable architecture from day 1
We choose the right stack and architecture for your current and future stage, avoiding technical debt that hinders growth.
Investor readiness
Technical due diligence without surprises. We prepare the technical documentation and storytelling that investors need to see.
Fast decisions with criteria
15+ years of experience in startups means we know what works and what doesn't. We avoid costly mistakes from the start.
Real flexibility
Minimum commitment of 3 months, cancellable with 30 days' notice. Enough time for the work to deliver results, without long ties. We scale the dedication up or down according to your startup's needs.
When does your startup need an external CTO?
There are specific moments in a startup's life where external technical leadership makes the difference between scaling or stagnating:
- You have a validated idea or first customers but don't know what tech stack to choose or how to structure development
- Your development team works without clear technical direction, generating technical debt and constant delays
- You need to prepare for an investment round and the technical due diligence concerns you
- You need to scale the technical team but don't know how to define roles or interview senior candidates
- The product grows and the current architecture won't handle the volume: you need a strategic refactoring
- You're a non-technical founder and want an expert by your side in conversations with the development team or CTO candidate
CTO as a Service vs. Development Agency: which do you need?
CTO as a Service (Collybrix)
- Defines strategy and technical roadmap
- Leads and mentors the development team
- Makes architecture and stack decisions
- Participates in business and investor meetings
- Guarantees long-term technical quality
- Flexible: 2-4 days/week as needed
Development Agency
- Executes the technical specifications you give them
- Requires direction and management from you
- Bills by hours or sprints, not by results
- Little involvement in business vision
- Can generate technical debt that's hard to manage
- Suitable when you already have clear technical direction
Frequently asked questions about CTO as a Service
When does my startup need a CTO as a Service?
Your startup needs a CTO as a Service when you have traction or a validated idea but can't afford a full-time CTO (salary €80,000-€150,000/year). Especially useful in pre-seed and seed stages, when you need to make critical technical decisions: what stack to choose, how to structure the development team, what architecture will support growth. If you're losing time on technical decisions or feel the development team lacks clear direction, it's time.
How much does a CTO as a Service cost with Collybrix?
The entry point is the Discovery Sprint: €2,500, fixed price, 14 days, fully deductible from your first monthly payment if you continue with CTO as a Service. After that, the retainer is sized with a personalized budget based on the outcome of the Discovery Sprint. As a market reference, a senior full-time CTO costs €12,000-€15,000/month.
What is the difference between an external CTO and a development agency?
An agency executes code. An external CTO decides what code to write and why. Collybrix's CTO as a Service brings strategic direction: defines the architecture, leads the technical team, prioritizes the roadmap based on the business, avoids technical debt and prepares the startup for investors and growth. It doesn't replace the development team — it directs and empowers it.
Can I hire a CTO as a Service first and then a full-time CTO?
Yes, and in fact it's the strategy we recommend. Collybrix's CTO as a Service establishes the technical foundations, processes and engineering culture. When you're in Series A with proven traction, you'll be much clearer on what CTO profile you need to hire, and the candidate will find a technically solid company that is more attractive to senior talent.
What does Collybrix's CTO as a Service include?
Our service includes: (1) Initial technical diagnosis and audit of the current situation, (2) Definition and prioritization of the technical roadmap, (3) Technology stack and architecture selection, (4) Development team leadership and mentoring, (5) Technical vendor management, (6) Preparation for investor technical due diligence, (7) Participation in key meetings with stakeholders and board.
Do you only work in Spain or across Europe?
We work with startups across Spain and also with European startups with operations in Spain. We are based in Madrid but operate remotely for most clients. For Madrid-based startups we also offer regular in-person meetings.
A real case
MVP in 10 weeks · 0% equity
Read the full story →“Collybrix saved the company — and I mean that literally. Without them, we would have missed demo day and lost the round.”