What is a Fractional CTO? A Guide From People Who've Done It Both Ways

We ran an agency for fifteen years before we stopped and rebuilt everything around equity partnerships and co-founder relationships. That shift taught us something important about the fractional CTO model: it fills a real gap, but it's not the only option — and for some founders, it's not even the right one.

This guide covers what a fractional CTO actually is, what they do, what they cost, and where the model works brilliantly. But we'll also be upfront about where it falls short, because we've seen both sides.

The short version

A fractional CTO is a senior technology leader who works with your company part-time — typically one to three days per week. They bring strategic thinking, architectural knowledge, and leadership experience without you having to put a £150k-plus salary on your payroll.

The model has exploded over the past few years. LinkedIn profiles with "fractional" alongside a C-suite title went from around 2,000 in 2022 to over 110,000 by late 2024. In the UK, roughly one in five businesses now uses some form of fractional leadership.

There's a reason it's caught on. For companies at the right stage, with the right needs, it genuinely works.

What a fractional CTO actually does

This varies depending on the company and stage, but here's the honest breakdown based on what we've seen across 25+ startup partnerships:

Technology strategy and roadmapping.: Working out what your tech should look like in six months, a year, two years — and plotting the realistic path to get there. Not a fantasy document that lives in a drawer. A working plan that your dev team can follow and your investors can believe in.

Architecture decisions.: Should you build this or buy it? Is your current stack going to hold when you triple your users? When someone suggests rewriting everything in the newest framework, is that genuine or shiny-new-thing syndrome? Whether you're running PHP, Python, Node.js, Go, or something else entirely, the underlying questions are the same. We've been through these decisions on platforms that scaled to hundreds of millions of users, and the expensive mistakes tend to look the same every time.

Team building.: Hiring developers is hard. Hiring the right ones for your stage and budget is harder. A fractional CTO helps write job specs, runs technical interviews, and often manages the development team directly until you have enough internal leadership to take over.

Technical due diligence.: If you're raising investment, your investors will want someone credible examining your codebase and architecture. If you're making an acquisition, you need to know what you're buying. This is where experience really counts, because the cost of missing something is enormous.

Vendor management.: Most startups outsource early development to an agency or offshore team. Someone needs to make sure they're building what you actually need, to a standard that won't fall apart when you need to scale or hand it off to an in-house team. Having spent fifteen years as the agency, we know exactly what questions to ask and what corners get cut when nobody senior is watching.

Security and compliance.: GDPR, PCI-DSS, SOC 2 — the compliance alphabet. It's not glamorous, but getting it wrong can kill a deal or land you a fine. A fractional CTO puts sensible protocols in place without over-engineering things for your stage.

Who typically hires a fractional CTO?

Non-technical founders: are the most common. You've got domain expertise, customers, and commercial instincts, but you need someone who can translate your vision into something that gets built, maintained, and scaled properly.

Companies between funding rounds.: You've outgrown the agency that built your MVP, but a £200k CTO salary doesn't make sense against your burn rate. A fractional CTO bridges that gap and often helps you get to the next round by professionalising your tech story.

Established businesses modernising their technology.: This isn't just a startup thing. Companies with ten or twenty years of history sometimes realise they need to modernise their systems but don't have anyone internally who can lead it.

Companies whose CTO has left.: Sometimes suddenly. A fractional CTO keeps the team focused and buys you time to make a proper permanent hire without panic.

Fractional CTO vs consultant vs technical co-founder

These get lumped together but they're fundamentally different.

A consultant: comes in, writes a report with recommendations, and leaves. Maybe they come back in a few months to see if you acted on any of it. They're advising from the outside.

A fractional CTO: rolls up their sleeves. They're not just advising — they're making architecture decisions, running interviews, reviewing pull requests, and dealing with it when production goes down on a Friday night. They have real accountability because they're embedded in your team.

A technical co-founder: goes further still. They take meaningful equity — often 10-25% — and their success is tied directly to yours. They're not billing you by the day; they're betting years of their time on your business succeeding. The difference in alignment is hard to overstate. When someone owns a chunk of your company, they care about things that a day-rate consultant never will — your unit economics, your customer retention, your long-term architecture choices.

This distinction matters a lot when you're choosing what's right for your situation. A fractional CTO is perfect for companies that need senior tech guidance one or two days a week. But if you're building something genuinely ambitious — a platform that needs to scale to millions of users, with complex architecture and a multi-year build — you might need someone with more skin in the game than a retainer arrangement provides.

How much does it cost?

We've written a full pricing guide separately, but the ballpark for the UK market:

Day rates:: £800-£1,600 depending on experience. Seed-stage specialists typically charge £800-£1,000. Someone with deep specialisation in AI, fintech, or cybersecurity will be north of £1,400.

Monthly retainers:: £3,000-£5,000 for one day per week, £5,000-£8,000 for two days. London rates run 20-30% higher than the rest of the UK.

The number that matters:: A full-time CTO in London costs roughly £190k-£255k in year one (salary, employer's NI, pension, benefits, recruitment fees, onboarding). A fractional CTO at two days a week runs about £72k annually. That's over £100k saved — and for many companies, it's the difference between eighteen months of runway and twelve.

There's also a hybrid model: that more companies are exploring: a reduced day rate combined with an equity stake. This aligns incentives better than pure cash — the CTO has a reason to care about long-term outcomes, not just billable hours. It also conserves your cash, which at the early stage is usually the scarcest resource you have.

When a fractional CTO isn't the right answer

We've always tried to be honest about this, because selling people the wrong thing is how you end up with unhappy clients and a bad reputation.

If you need someone writing code forty hours a week: , you need a senior developer or tech lead, not a CTO. The CTO title implies strategic leadership — architecture, hiring, roadmapping — not being your most productive programmer.

If you're a Series C company with fifty engineers: , you almost certainly need a full-time CTO who's in the room every day. The fractional model works best when the organisation is small enough that one or two days a week of senior attention can genuinely move the needle.

If your main problem is execution, not strategy.: Some companies have a perfectly sound technical strategy — they just need more hands to build it. A fractional CTO won't fix a resourcing problem. You might need more developers or a delivery manager.

If you're building something that needs deep, multi-year technical commitment.: A fractional CTO can get you started, but if you're building a platform that's going to serve millions of users and needs someone thinking about your architecture every single day, you might need a technical co-founder — someone who's invested in the outcome, not just showing up twice a week.

How to find a good one

A few things to look for:

Relevant experience, not just impressive titles.: Someone who was CTO of a Series D fintech is probably wrong for your pre-seed healthtech startup. Stage matters. Industry matters. Find someone who's solved problems that look like yours.

Ask about failures.: Every experienced technologist has horror stories — migrations that went sideways, hires that didn't work out, bets on the wrong technology. If they can't talk openly about what went wrong, they haven't been around long enough or they're not being straight with you.

Check their availability.: Some fractional CTOs juggle two or three clients. Some take on six. That matters when something urgent comes up. Ask how many concurrent engagements they run.

Get references from founders, not LinkedIn.: Actual conversations with people they've worked with. Ask specifically about communication, reliability, and what happened when things went wrong.

Understand their commercial model.: Are they purely day-rate? Do they offer equity-aligned arrangements? Someone willing to take a stake alongside a reduced rate is telling you something about their confidence in what they bring to the table.

The bottom line

The fractional CTO model is here to stay. For startups that need experienced technology leadership without the full-time price tag, it's a smart, proven option. The talent pool is deep, the pricing has become competitive, and the structure works.

But it's not the only option. Depending on your ambition, your stage, and the complexity of what you're building, you might need a consultant, a fractional CTO, or a full technical co-founder. The honest answer depends on your specific situation — not on who's selling what.

Read next:: How much does a fractional CTO cost? or CTO as a Service: what it means and whether you need it.

Cooply is a technical founding team based in South Wales and Yorkshire. We partner with startups as equity co-founders, fractional CTOs, or on a hybrid basis — taking on 3-4 new ventures each year. If you want to talk about which model fits your situation, get in touch.