What Is a Fractional CTO?

A fractional CTO is a part-time, senior technical executive who sets architecture and technology direction for a company without holding a full-time seat. They make the calls a technical co-founder would make - stack, build-vs-buy, hiring, roadmap - on a schedule sized to the company's stage, not a 40-hour week.

## What a fractional CTO actually does

The title covers four recurring jobs, in roughly this order of weight:

1. **Architecture decisions.** What the system looks like at the database, service, and integration layer, made before code gets written rather than refactored in after launch.
2. **Tech-stack choices.** Which language, framework, and hosting model fit the team's skill set, the compliance load, and the runway - not whichever stack is trending.
3. **Vendor and build-vs-buy calls.** When to license a platform, when to build in-house, and how to evaluate a vendor's claims about their own AI or infrastructure before signing.
4. **Hiring input and roadmap translation.** Writing job specs a non-technical founder can't write alone, sitting in on senior interviews, and turning a business goal ("cut onboarding time in half") into a sequenced technical plan.

What they don't do: write production code every day, sit in daily standups as an implementer, or replace an engineering team. A fractional CTO directs the work. Someone else - a pod, a contractor, an in-house hire - builds it.

## Why startups win with a fractional CTO

The math is asymmetric. A wrong architecture decision made in month two - the wrong database for the access pattern, a monolith that should have been two services, an auth system that can't support the compliance requirement six months out - costs far more to unwind than it would have cost to get right the first time. Rebuilding a data layer under a live customer base runs into months of dedicated engineering time that a startup usually doesn't have.

A fractional CTO exists to catch that decision before it's made. The role costs a fraction of a full-time executive salary and shows up exactly when the decision needs making, which is why it wins for a company that has one or two architecture-critical calls a quarter, not one every week. For the deeper responsibilities of the seat and how the engagement is usually priced, see our breakdown of [what a CTO does](/blog/what-is-a-cto) and the [fractional CTO services](/blog/fractional-cto-services) most companies actually buy.

## Do you need one? A short checklist

Answer yes to two or more and the case is strong:

- No technical co-founder, and the founding team can't independently evaluate a vendor's or engineer's claims.
- Past MVP and heading into a scaling decision - new data model, multi-tenant architecture, or a compliance requirement (HIPAA, SOC 2) that changes how the system has to be built.
- An AI vendor or in-house team is proposing something (a model, an agent framework, a "compliant" claim) that nobody on staff can independently verify. This is a live problem: [McKinsey's 2025 State of AI survey](https://www.mckinsey.com/~/media/mckinsey/business%20functions/quantumblack/our%20insights/the%20state%20of%20ai/november%202025/the-state-of-ai-2025-agents-innovation_cmyk-v1.pdf) found 88 percent of organizations now use AI in at least one business function, up from 78 percent a year earlier - most of them without a technical executive who can pressure-test what a vendor is actually selling.
- The team is hiring its first senior engineers and nobody can run a technical interview that separates a strong candidate from a confident one.
- A board or investor is asking architecture or security questions the founder can't answer without guessing.

If none of these apply, the role is premature. A strong pod lead and a clear spec cover most early-stage needs without adding an executive seat. For actual dollar ranges across engagement types, see our [fractional CTO cost and rates](/blog/fractional-cto-cost-and-rates) guide.

## How this compares to a full-time CTO, an advisor, and a build pod

| Model | Time commitment | Owns architecture day to day | Best fit |
|---|---|---|---|
| Full-time CTO | 40+ hrs/week, one company | Yes | Post-Series A, engineering org of 10+ |
| Fractional CTO | Few hours/week to a few days/month | Sets direction, doesn't implement | Pre-seed to Series A, no technical co-founder |
| Technical advisor | Ad hoc, occasional calls | No | Founder who wants a sounding board, not decisions made for them |
| Build pod | Full-time on your codebase, weekly ship | Pod lead owns it | Company that needs the work done, not just directed |

A **full-time CTO** is the right hire once the engineering org is big enough to need daily management - usually past Series A, with ten or more engineers reporting up through layers.

A **technical advisor** is lighter than a fractional CTO: they'll weigh in when asked, but they don't own outcomes or sit accountable for a roadmap. Useful for a second opinion, not for running the technical side of the business.

A **build pod** is a different model entirely, and often the better fit once direction is set. In our own [pods](/pods), the pod lead owns scope and architecture day to day, backed by senior engineers who build and QA who tests, 2-5 engineers depending on plan. The pod lead makes the same class of decision a fractional CTO makes, but does it while shipping the code every week rather than advising from the side. See our [how it works](/how-it-works) page for how a pod starts within five business days and ships the first working piece in week one or two.

Companies often need both at different points: a fractional CTO to set the technical direction and evaluate vendors early, then a pod once there's a defined build to execute against.

## The short version

A fractional CTO sets direction, not code. They cost less than a full-time executive, show up when an architecture or vendor decision needs making, and step back once the direction is set. If the gap is "we need someone to decide," that's a fractional CTO. If the gap is "we need someone to build it," that's a pod with a lead who owns architecture day to day - and the two often work in sequence, not instead of each other.