What Should a CTO Actually Do? (No-Nonsense Guide for Non-Technical Founders)

A CTO makes strategic technology decisions, prevents expensive technical mistakes, manages technical teams, and ensures your technology supports business growth. They spend 80% of time on strategy and leadership, not writing code. Most UK businesses under £5M revenue need this expertise 2-3 days per week, not full-time at £180,000+/year.

You've hired developers. They're building your product. But when they tell you "we need to rebuild the entire backend" or "this will take six months," you've no idea if they're right or wasting your money.

That's what a CTO solves. But most non-technical founders misunderstand what CTOs actually do day-to-day, which leads to hiring the wrong person or paying £150,000+ for someone who spends their day writing code instead of making strategic decisions.

I've worked with 15+ UK businesses who hired technical leadership. Half got it wrong the first time. The ones who succeeded understood what a CTO should actually be doing before they hired.

What is a CTO's primary responsibility?

A CTO's primary responsibility is making technology decisions that align with business goals whilst preventing expensive technical mistakes. They translate business requirements into technical strategy, not implement the strategy themselves.

A Manchester e-commerce company wanted to expand internationally. Their developers recommended rebuilding everything with microservices architecture at £120,000 cost. The CTO asked one question: "What revenue do we need from international markets to justify this investment?"

Answer: £500,000+ annually. Current international revenue: £45,000. The CTO recommended a £12,000 solution using their existing platform with localisation. They launched in three countries within two months.

That's what CTOs do. They make technical decisions based on business impact, not technical perfectionism.

What does a CTO do daily?

CTOs spend their day reviewing technical decisions, unblocking teams, evaluating vendors, managing technical risk, and ensuring technology supports business objectives. A typical day includes architecture reviews, team leadership, vendor meetings, and strategic planning, not writing production code.

Breaking down a typical CTO's week for a £3M revenue UK business:

30% Strategic Planning

• Technology roadmap aligned with business goals
• Build vs buy decisions
• Infrastructure and architecture planning
• Technical debt management
• Budget planning and resource allocation

25% Team Leadership

• Unblocking developers on technical decisions
• Code review oversight (not doing reviews, ensuring they happen)
• Hiring and team structure decisions
• Performance management
• Skills development and training planning

20% Vendor and Stakeholder Management

• Evaluating development agencies and contractors
• SaaS and infrastructure vendor negotiations
• Board reporting on technology status
• Customer technical conversations (for B2B)
• Security and compliance management

15% Risk Management

• Security audits and vulnerability management
• Disaster recovery planning
• Technical due diligence (if raising funding)
• Compliance (GDPR, industry-specific regulations)
• Technical debt assessment

10% Hands-On Technical Work

• Proof-of-concept for critical decisions
• Emergency firefighting (rare, but happens)
• Architecture documentation
• Critical code reviews
• Technical interviews

Notice: only 10% hands-on coding. If your CTO spends most of their time writing code, they're not doing the strategic work you're paying them for.

How does a CTO differ from a senior developer or tech lead?

CTOs focus on business-aligned technology strategy across the entire organisation, whilst tech leads manage technical execution within a team, and senior developers solve complex technical problems in code. The key difference is scope and strategic responsibility.

A London FinTech hired a brilliant senior developer at £85,000, expecting them to make architecture decisions and manage vendors. Eighteen months later they'd spent £200,000 fixing technical choices that developer made without understanding business context.

The senior developer wasn't incompetent. They were asked to do a job they weren't hired for and lacked the experience to perform.

Senior Developer Focus:

• Writes complex code and solves difficult technical problems
• Reviews other developers' code
• Mentors junior developers on coding techniques
• Implements features efficiently
• Optimises performance and fixes bugs

Tech Lead Focus:

• Manages day-to-day technical execution for a team
• Makes tactical technology decisions within defined scope
• Coordinates between developers and product managers
• Ensures code quality and development practices
• Still writes code 40-60% of time

CTO Focus:

• Makes strategic technology decisions across entire business
• Aligns technology roadmap with business goals
• Manages technical risk and prevents expensive mistakes
• Evaluates and negotiates with vendors
• Represents technology at board level
• Writes code rarely (under 10% of time)

Need help understanding which role you actually need? Read our complete comparison of CTO vs Tech Lead vs Senior Developer.

What technology decisions should a CTO make?

CTOs make decisions on technology stack, build vs buy, vendor selection, architecture, security, infrastructure, team structure, and technical hiring. Any technical decision that affects business risk, cost over £10,000, or impacts multiple teams falls under CTO responsibility.

1. Technology Stack Decisions

Choosing programming languages, frameworks, databases, and infrastructure that balance current needs with future scalability. A CTO evaluates stack decisions based on hiring availability (can we find developers?), cost, performance requirements, and long-term maintainability.

Example: A Bristol SaaS company wanted to rebuild in Rust because developers read it was "faster." CTO analysis showed their bottleneck was database queries, not application speed. They optimised queries instead, saving £80,000 and four months of development.

2. Build vs Buy Decisions

Determining whether to build custom solutions or buy existing software. CTOs calculate total cost of ownership, including maintenance, over 3-5 years.

Example: Authentication system. Building custom: £25,000 upfront, £15,000 annually maintenance. Buying Auth0: £5,000 annually. CTO chose Auth0, saving £65,000 over three years.

3. Vendor and Agency Evaluation

Vetting development agencies, SaaS providers, and contractors. CTOs prevent bad vendor relationships that waste £50,000-150,000.

Example: A Birmingham business received quotes from three agencies: £45,000, £65,000, and £120,000 for the same project. CTO identified the £45,000 agency used offshore developers without project management, the £65,000 agency had relevant experience and provided realistic timeline, and the £120,000 agency was overpriced. Choosing correctly saved £55,000.

4. Security and Compliance

Ensuring systems meet security standards and regulatory requirements. CTOs prevent data breaches that cost £100,000-500,000+ in fines and reputation damage.

Example: Pre-funding due diligence revealed a company stored passwords in plain text. Investors nearly walked away. Would've cost the company a £2M funding round. CTO oversight prevents these disasters before they happen.

5. Technical Debt Management

Balancing speed of development with code quality. CTOs prevent "move fast and break things" culture from creating £200,000 rewrites two years later.

Rule of thumb: allocate 20-30% of development time to technical debt. CTOs enforce this discipline even when stakeholders want "just one more feature."

When should a CTO be writing code?

CTOs should write code only for proof-of-concepts, critical emergencies, or when evaluating technical approaches firsthand. If your CTO spends more than 20% of time writing production code, they're not focusing on strategic work you need from the role.

Acceptable coding scenarios for CTOs:

Proof-of-Concept (5-10% of time)

Testing new technologies or architectures before committing the team. A CTO might spend two days building a prototype with a new framework to evaluate if it's worth adopting.

Emergency Response (Rare)

Critical production issues when all hands needed. Even then, CTO's primary role is coordinating response and communicating with stakeholders, not fixing the bug themselves.

Technical Evaluation (5% of time)

Code reviews of critical architecture changes or security-sensitive code. Not reviewing every pull request, but strategic technical decisions.

Technical Interviews

Pair programming during senior developer interviews to assess technical capability.

A Leeds business had a "CTO" who spent 70% of time writing features. When asked who was making architecture decisions and managing technical risk, answer was "nobody." They were paying £140,000 for a senior developer doing CTO in title only.

After three years, technical debt forced a £180,000 platform rebuild that proper CTO oversight would've prevented.

What are the biggest mistakes CTOs make?

The biggest CTO mistakes are over-engineering solutions, staying too hands-on with code, making technology decisions without business context, poor communication with non-technical stakeholders, and failing to manage technical debt. These mistakes cost businesses £50,000-300,000+ in wasted development and technical rewrites.

Mistake 1: Over-Engineering

Building for scale you won't reach for five years. A startup at £200,000 revenue doesn't need the infrastructure of a £50M company.

Example: A CTO designed a microservices architecture for a pre-revenue startup with two developers. Added six months to launch, burned through runway. Simpler monolith would've gotten them to market and revenue faster.

Cost: £120,000 in unnecessary development time plus delayed revenue.

Mistake 2: Staying Too Hands-On

Writing code instead of strategic planning. Makes CTO a bottleneck because they're the only one who understands critical systems.

Example: CTO wrote core payment processing code. When they left the company, nobody understood how it worked. Cost £85,000 to document and refactor.

Mistake 3: Technology-First Thinking

Making decisions based on what's technically interesting instead of what supports business goals.

Example: CTO insisted on rebuilding working system because "the new framework is better." Cost £95,000, added zero business value, delayed roadmap by four months.

Mistake 4: Poor Non-Technical Communication

Using jargon in board meetings instead of translating technical concepts into business impact.

Bad: "We need to refactor the monolithic architecture into microservices for improved scalability."

Good: "Our current system handles 500 concurrent users. At £5M revenue we'll hit 2,000 concurrent users and need infrastructure upgrades. Three options: spend £40,000 now, £75,000 when we hit capacity, or £200,000 emergency fix if we wait too long. Recommend spending £40,000 in Q3."

Mistake 5: Technical Debt Denial

Ignoring technical debt until it forces expensive rewrites. Every month of technical debt accumulation costs 2-3x more to fix later.

Example: CTO prioritised only new features for 18 months. System became so unstable developers spent 60% of time fixing bugs instead of building features. Eventually required £150,000 refactor plus lost revenue from delayed features.

How does a CTO work with developers?

CTOs work with developers by setting technical direction, unblocking decisions, providing context on business priorities, and ensuring quality standards without micromanaging. They lead through technical vision and experience, not by reviewing every line of code.

Effective CTO-developer relationship:

Weekly Technical Sync (30-60 minutes)

• Review progress on strategic initiatives
• Unblock technical decisions developers are stuck on
• Provide business context for priorities
• Discuss technical debt and quality concerns

Architecture Reviews (As needed)

• Review proposals for significant technical changes
• Challenge assumptions and identify risks
• Provide experience-based guidance
• Final decision on approach

Quarterly Technical Planning

• Align technical roadmap with business goals
• Allocate time for technical debt
• Plan infrastructure and scaling work
• Set team technical objectives

A Nottingham business improved development speed by 40% after their fractional CTO implemented structured decision-making. Developers previously wasted 10-15 hours weekly debating technical approaches. CTO established clear decision frameworks and made final calls within 24 hours.

Developers became more productive and less frustrated. Clear decisions beat perfect decisions.

What should you expect from a CTO in the first 90 days?

In the first 90 days, a CTO should assess current technology, identify critical risks, establish team processes, create technology roadmap aligned with business goals, and make 2-3 high-impact decisions. Expect documented findings, not completed projects.

Days 1-30: Assessment

• Audit existing codebase, infrastructure, and architecture
• Interview developers and understand team dynamics
• Document current state and technical debt
• Identify critical security or stability risks
• Review vendor contracts and relationships
• Understand business goals and revenue model

Deliverable: Technical assessment report with risk prioritisation.

Days 31-60: Planning

• Create 6-12 month technology roadmap
• Establish development processes (code review, testing, deployment)
• Prioritise technical debt alongside features
• Set measurable technical objectives
• Plan critical hires or contractor needs

Deliverable: Technology roadmap with budget estimates and resource plan.

Days 61-90: Execution

• Implement quick wins (usually security or stability improvements)
• Begin highest-priority technical initiatives
• Establish regular team sync and reporting
• Make build vs buy decisions on pending items
• Start vendor renegotiations if costs high

Deliverable: Visible progress on 2-3 high-impact initiatives plus established ongoing processes.

A Cambridge business brought in a fractional CTO. Within 90 days, they'd identified £45,000 in unnecessary SaaS costs, prevented a £80,000 architecture mistake, and implemented development processes that reduced bugs by 35%.

Return on investment from first 90 days: £125,000+ whilst paying £12,000 for fractional services.

Do you need a full-time CTO or fractional CTO?

Businesses under £5M revenue typically need fractional CTO services 2-3 days per week, not full-time at £180,000+/year. Full-time CTOs make sense above £10M revenue or with 15+ person technical teams requiring daily leadership.

Fractional CTO works when you need:

• Strategic technology decisions without daily execution oversight
• Architecture and vendor guidance 2-5 days monthly
• Technology leadership for 5-10 person technical team
• Board-level technology expertise without full-time cost
• CTO experience at £3,000-8,000/month instead of £15,000+/month

Full-time CTO makes sense when you have:

• 15+ person technical team requiring daily leadership
• Multiple product lines with complex technical dependencies
• £10M+ revenue with technology as core differentiator
• Regulatory requirements demanding full-time technical oversight
• Funding and business scale justifying £180,000-350,000 annual cost

Most UK businesses between £1-10M revenue waste money hiring full-time CTOs before they're needed. They end up with expensive senior developers instead of strategic technical leaders.

See our complete analysis in Fractional CTO UK: What You'll Actually Pay vs Full-Time including real cost breakdowns and decision framework.

How do you know if your CTO is doing a good job?

A good CTO reduces technical risk, enables faster development over time, makes cost-effective technology decisions, prevents expensive mistakes, and translates technical complexity into clear business impact. Measure results, not activity.

Key Performance Indicators:

1. Development Velocity Increases

Teams ship features faster over time, not slower. Good CTOs remove bottlenecks and technical debt, making development easier month over month.

Bad sign: Development keeps slowing down due to accumulating technical debt.

2. Technical Decisions Have Clear Business Rationale

You understand why technology investments matter and their expected return. Good CTOs explain "we're spending £40,000 on infrastructure because it prevents £200,000 emergency later and supports £5M revenue target."

Bad sign: "We need to do this technical work" with no business justification.

3. No Surprise Technical Costs

Infrastructure, vendor costs, and maintenance are planned and predictable. Good CTOs forecast technical costs and negotiate favourable vendor terms.

Bad sign: Regular £10,000-50,000 "unexpected" technical expenses.

4. Security and Stability Incidents Decrease

Production issues, security vulnerabilities, and downtime reduce over time. Good CTOs implement monitoring, testing, and processes that catch problems before they affect customers.

Bad sign: Regular production fires and security scares.

5. Technical Team Retention Strong

Developers stay and develop their skills. Good CTOs create environment where technical team grows and doesn't want to leave.

Bad sign: High developer turnover (50%+ annually) with exit interviews mentioning technical dysfunction.

6. Successful Technical Due Diligence

If raising funding, investors approve technology in due diligence without major concerns. Good CTOs build systems that pass investor scrutiny.

Bad sign: Funding delayed due to technical debt, security issues, or architecture concerns.

Want to ensure you hire the right CTO? Use our 17 Questions to Ask When Hiring a Fractional CTO checklist.

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Key Takeaways

CTOs make strategic technology decisions aligned with business goals, spending 80% of time on strategy, not coding. They prevent expensive technical mistakes, manage technical teams, and ensure technology supports growth without wasting money.

The difference between CTOs and senior developers or tech leads is scope and strategic responsibility. CTOs focus on organisation-wide technology strategy, tech leads manage team execution, and senior developers solve complex technical problems.

Good CTOs reduce technical risk, enable faster development over time, make cost-effective decisions, and translate technical complexity into business impact. Measure them on results like development velocity, technical cost predictability, and successful business outcomes, not lines of code written.

Most UK businesses under £5M revenue need fractional CTO services 2-3 days per week, not full-time at £180,000+/year. Strategic technology guidance matters more than daily presence for businesses at this scale.

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About the Author

Jake Holmes has worked with 15+ UK businesses (£1-10M revenue) on technology leadership decisions. He's helped companies decide between fractional and full-time CTOs, recruited technical leaders, and prevented £100,000+ in bad hiring decisions. Before founding Grow Fast, Jake was a software engineer and technical lead, giving him the technical depth most consultants lack.

Connect: jake@grow-fast.co.uk | LinkedIn | Book consultation

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Grow Fast helps UK businesses (£1-10M revenue) make smart technology decisions without wasting money. Our Fractional CTO services provide strategic technical leadership 2-5 days per month, saving you £200,000+ vs hiring full-time whilst getting the expertise you actually need. Book a free 30-minute call to discuss your technical leadership needs.