What is a Fractional CTO?
A fractional CTO is a senior technology executive who provides part-time technical leadership to companies that need strategic guidance but aren't ready for—or can't afford—a full-time Chief Technology Officer.
Unlike consultants who provide advice and leave, a fractional CTO becomes embedded in your organization. They attend your standups, join your Slack channels, participate in investor meetings, and take accountability for technical outcomes.
The "fractional" model has become increasingly popular among UK startups, particularly in the pre-seed to Series A stages. It allows founders to access executive-level expertise while preserving runway and avoiding premature scaling of their leadership team.
Key Point
A fractional CTO typically works 8-20 hours per week, costs 60-80% less than a full-time hire, and can start within 1-2 weeks versus 3-6 months for a permanent search.
What Does a Fractional CTO Do?
The responsibilities of a fractional CTO vary based on your startup's stage and needs, but typically include:
Technical Strategy & Architecture
- Defining technical roadmaps aligned with business goals
- Making build vs. buy decisions
- Selecting technology stacks and frameworks
- Designing scalable system architectures
- Establishing coding standards and best practices
Team Building & Leadership
- Defining engineering team structure
- Hiring and interviewing developers
- Mentoring junior engineers and tech leads
- Establishing engineering culture and processes
- Managing contractors and development agencies
Investor & Board Relations
- Attending investor meetings as the technical voice
- Preparing technical due diligence materials
- Creating board presentation content
- Answering VC technical questions
Operational Excellence
- Implementing DevOps and CI/CD pipelines
- Security architecture and compliance
- Performance optimization
- Vendor negotiation (cloud providers, tools)
When Should You Hire a Fractional CTO?
The right time to hire a fractional CTO depends on your specific situation, but here are the most common triggers:
You're a Non-Technical Founder
If you're building a technology product without technical co-founder, you need someone who can translate your vision into technical reality, evaluate developers' work, and make informed architecture decisions.
You're Preparing to Fundraise
Investors will ask detailed technical questions. Having a credible CTO (even fractional) in investor meetings significantly increases your chances of closing a round. They'll also help prepare due diligence materials.
Your Development Is Stalling
If you have developers but lack senior leadership, you might see symptoms like: missed deadlines, accumulating technical debt, team conflicts, or difficulty shipping features. A fractional CTO can diagnose and fix these issues.
You Can't Afford a Full-Time CTO
A full-time CTO in London costs £150,000-£220,000+ in salary alone, plus equity, benefits, and recruitment fees. If that's not in your budget but you need the expertise, fractional is the answer.
Signs You Need a Fractional CTO
- • You're spending more time managing developers than running the business
- • Technical decisions are being made without strategic oversight
- • Investors are asking questions you can't confidently answer
- • Your product roadmap feels disconnected from technical reality
- • Development costs are spiraling without clear ROI
How Much Does a Fractional CTO Cost?
Fractional CTO costs in the UK vary based on experience level, engagement intensity, and industry specialization. Here's what to expect:
| Engagement Level | Hours/Week | Monthly Cost | Annual Equivalent |
|---|---|---|---|
| Light Touch | 4-8 hours | £2,000-£4,000 | £24,000-£48,000 |
| Standard | 8-12 hours | £4,000-£8,000 | £48,000-£96,000 |
| Intensive | 12-20 hours | £8,000-£15,000 | £96,000-£180,000 |
Cost Comparison: Fractional vs Full-Time
A full-time CTO in London typically costs:
- Base salary: £150,000-£220,000
- Employer NI: £18,000-£26,000
- Pension: £6,000-£9,000
- Benefits: £5,000-£15,000
- Equity: 1-4% (immediate dilution)
- Recruitment: £30,000-£50,000 (one-time)
Total Year 1: £210,000-£320,000+ plus equity dilution
A fractional CTO at the "Standard" level costs £48,000-£96,000 annually—60-80% savings with no equity dilution and no recruitment fees.
Fractional CTO vs Full-Time CTO
| Factor | Fractional CTO | Full-Time CTO |
|---|---|---|
| Cost | £48k-£180k/year | £210k-£320k/year |
| Equity | None typically | 1-4% |
| Time to Start | 1-2 weeks | 3-6 months |
| Availability | 8-20 hours/week | 40+ hours/week |
| Flexibility | Scale up/down easily | Fixed commitment |
| Risk | Low (monthly terms) | High (severance, rehiring) |
| Best For | Pre-seed to Series A | Series A+ with 15+ engineers |
Choose fractional when: You need strategic leadership but don't require 40+ hours of CTO time weekly, your runway is under 18 months, or you want to de-risk before committing to a full-time hire.
Choose full-time when: You have 15+ engineers requiring daily leadership, technology is your core differentiator requiring constant innovation, or you've secured significant funding and can justify the investment.
Read our detailed analysis: Fractional CTO vs Full-Time CTO →
Fractional CTO vs Development Agency
Many founders consider hiring a development agency instead of a fractional CTO. Here's how they compare:
Development Agency
- Focus: Building software to your specifications
- Accountability: Delivering agreed scope on time
- Strategic Input: Limited—they execute, you decide
- Knowledge Retention: Stays with the agency
- Cost: £50,000-£200,000+ per project
Fractional CTO
- Focus: Technical strategy and leadership
- Accountability: Long-term technical success
- Strategic Input: High—they shape technical direction
- Knowledge Retention: Stays with your company
- Cost: £48,000-£180,000 per year
The Best of Both Worlds
Many startups combine both: a fractional CTO to define architecture, oversee quality, and make strategic decisions, while an agency or contractors handle development execution. The fractional CTO ensures the agency builds the right thing, the right way.
How to Choose a Fractional CTO
Green Flags
- Relevant industry experience — They've built similar products before
- Founder empathy — They've been in your shoes, not just worked at big companies
- Execution focus — They talk about outcomes, not just methodologies
- Clear communication — They can explain complex topics simply
- Strong references — Past clients willing to vouch for them
Red Flags
- All theory, no practice — Lots of frameworks, no shipping stories
- No team experience — Great individual contributors don't always make good leaders
- Overcommitted — Managing 10+ clients means you won't get attention
- Equity-first pricing — Fractional should be cash-based; equity is for full-time
- Can't get technical — If they can't discuss architecture specifics, question their depth
Questions to Ask
- "Walk me through a technical decision you made that didn't work out. What did you learn?"
- "How do you handle disagreements with the engineering team?"
- "What's your availability for investor meetings and urgent issues?"
- "Can I speak with 2-3 past clients?"
- "What does a successful 90-day engagement look like for us?"
Working with a Fractional CTO
To get the most value from your fractional CTO engagement:
1. Define Clear Outcomes
Instead of vague goals like "provide technical leadership," set specific objectives:
- Complete technical due diligence documentation by Q2
- Hire 2 senior engineers within 60 days
- Reduce deployment time from 2 days to 2 hours
- Define 12-month technical roadmap
2. Integrate Properly
Treat your fractional CTO as a team member, not an outsider:
- Add them to Slack, email, and project management tools
- Include them in relevant meetings
- Introduce them to the team with appropriate authority
- Give them access to codebase and documentation
3. Establish Communication Rhythm
- Daily: Async availability on Slack for quick questions
- Weekly: 30-60 minute sync with founders
- Monthly: Progress review and goal adjustment
- Quarterly: Strategic planning session
Transitioning to a Full-Time CTO
A good fractional CTO should help you eventually outgrow them. Here's how the transition typically works:
Option 1: Promote from Within
If you have a strong VP Engineering or Tech Lead, the fractional CTO can mentor them into the CTO role while gradually reducing their own involvement.
Option 2: Hire Full-Time
The fractional CTO helps define the full-time role, participates in interviews, and ensures a smooth knowledge transfer to their replacement.
Option 3: Convert to Advisory
Many fractional CTOs transition to a lighter advisory role (2-4 hours/month) once a full-time CTO is in place, providing ongoing strategic guidance.
Frequently Asked Questions
What is the difference between a fractional CTO and a consultant?
A fractional CTO is embedded in your team and accountable for outcomes, not just advice. They attend standups, participate in hiring, and own technical decisions. Consultants typically provide recommendations and leave implementation to you.
How many hours per week does a fractional CTO work?
Typically 8-20 hours per week, depending on your stage and needs. Early-stage startups often start with 8-12 hours, scaling up during critical periods like fundraising or major product launches.
Can a fractional CTO help with fundraising?
Yes. Fractional CTOs often attend investor meetings, prepare technical due diligence materials, and help answer technical questions from VCs. This is one of the most valuable contributions during fundraising rounds.
What industries do fractional CTOs work in?
Fractional CTOs work across all technology sectors. Common industries include fintech, healthtech, B2B SaaS, e-commerce, marketplaces, and proptech. The key is matching industry experience to your specific needs.
How long do fractional CTO engagements typically last?
Engagements typically range from 6 months to 2+ years. Some startups use fractional CTOs as a bridge until they can afford full-time leadership; others maintain the relationship through Series A and beyond.
Do fractional CTOs write code?
It depends on the engagement. Some fractional CTOs are hands-on and contribute code, especially at early stages. Others focus purely on strategy, architecture, and team leadership. Clarify expectations upfront.
Need a Fractional CTO?
We provide fractional CTO services for UK startups from pre-seed to Series A. Book a free discovery call to discuss your needs.
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