Fractional CTO for SaaS Scale-Ups: What Changes at £10m ARR

Getting a SaaS business to roughly £10m in annual recurring revenue and getting it past that point are different problems, even though they can look similar from the outside. The technology decisions that got the product built fast and the first hundred customers won are, more often than not, exactly the decisions that start creating friction once the business is trying to scale further.

This isn't a story about anyone getting it wrong early on. Moving fast and taking on technical shortcuts is usually the correct call when the priority is proving the product works. The problem is that those shortcuts don't announce themselves as debt until the business is trying to do something they weren't built for.

Where the friction shows up

Enterprise buyers start asking security and compliance questions the product wasn't built to answer cleanly. Infrastructure that scaled fine for the first wave of customers starts showing strain, in cost, in reliability, or in both, as usage patterns change. An engineering team that grew organically, hire by hire, without a deliberate structure, starts showing the cracks: unclear ownership, inconsistent practices between squads, and a roadmap that's really just whoever shouts loudest getting their feature built next.

What a fractional CTO actually changes

A fractional CTO brought in at this stage isn't there to rebuild the product from scratch. Most of the time that would be the wrong call entirely. The job is to separate what genuinely needs re-architecting from what just needs better process wrapped around it, and to build a plan the business can actually resource and execute against, rather than a wish list.

That typically means: a technical debt register that's prioritised against commercial impact rather than engineering preference, a security and compliance posture that can survive a serious enterprise buyer's due diligence, an engineering structure with clear ownership as the team grows past the size where everyone can just talk to everyone, and infrastructure decisions made with the next stage of growth in mind, not just the current one.

Why this is a fractional role, not a permanent hire, at this stage

Getting a SaaS business through this specific transition is a defined, high-intensity piece of work with a natural end point: the point at which the technology function has a plan, a structure and a debt register, rather than accumulated shortcuts and hope. Bringing in a fractional CTO for that phase, rather than committing to a full-time hire before knowing exactly what the role needs to look like on the other side of it, lets the business get through the transition with experienced leadership without over-committing before the shape of the permanent role is clear.