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How to choose a fractional CTO (when you can't judge one)

4 min readSimon Piscitelli
How to choose a fractional CTO: five brass keys on one ring held to the light, a hand testing the one cut differently.

To choose a fractional CTO you have to solve a structural problem: the whole reason you are hiring one is that nobody in the business can independently evaluate technical seniority, and now you have to evaluate technical seniority. You cannot fix that by reading CVs harder. You fix it by testing proxies that do not require you to judge the code: demonstrated range, outcomes the candidate personally owned, and incentives that reward telling you the truth.

That is what this checklist is. Five checks, each with the question to ask, followed by the red flags that should take a candidate straight off the shortlist.

How to choose a fractional CTO: the five checks

1. Range of mode. The role will demand three different kinds of work from the same person: making the calls, building and calibrating the team, and getting hands-on in the code when a blocker demands it. Most of the market sells exactly one of those modes: advisers who have not shipped in years, or builders who have never owned a commercial call. The gap between modes is where engagements quietly fail. Ask for a concrete, recent example of each: a call they made and defended, a team they built or restructured, code they personally shipped. Anyone with genuine range answers all three in specifics within a minute. PIMASI’s engagements are built around that range, and it is the first thing worth testing in anyone you shortlist, including us.

2. Outcomes owned, not projects attended. Seniority on paper is exposure; seniority that matters is ownership. Ask what business metric moved because of them, and what they personally did to move it. “We migrated to a new platform” is attendance. “The rebuild I stopped saved the client a six-figure quote, and the refactor I ran instead shipped in eight weeks” is ownership. Listen for the P&L in the answer: a genuine senior can explain every technical call in terms of cost, speed, or risk.

3. The walk-away test. Ask about the last prospective client they told “you don’t need me”. A fractional whose every discovery call ends in an engagement is selling capacity, not judgement. The answer costs them nothing to fake in theory, but in practice the specifics give it away: who it was, what they advised instead, what it cost them to say. An honest “no engagement” early is the cheapest signal of calibration you will ever buy, and the person you want is the one whose engagement is designed to produce it. Independence of judgement is most of the value; a straight answer on whether you need this at all is part of what you are paying for.

4. Engagement shape. Ask how the engagement is defined. The strong answer names an outcome and decision rights: what will be true in ninety days, which calls they own, which stay with you. The weak answer is a metered diary, two days a week of unspecified presence, renewed by default. Cost follows shape, and a diary-shaped engagement drifts because nothing defines what done looks like. You are not buying attendance; one of the outcomes an engagement should be built to produce is cutting the time you personally spend managing software by 90%, and that only happens when the engagement is defined by outcomes rather than hours.

5. Who does the work. Ask directly: is the person in this conversation the person who will make the calls, run the interviews, and write any code the engagement needs? Some fractional arrangements are fronted by a senior face and delivered by a rotating bench, which reintroduces the translation gap you are paying to remove. The answer you want is unambiguous: the judgement and the delivery come from the same person you are talking to.

The red flags that end a shortlist

  • Advice-only history: no software personally shipped in years, and examples that all end at the recommendation.
  • Delivery-only history: plenty shipped, but no seat at a commercial decision and no example of changing a business outcome.
  • Cannot explain a technical call in P&L terms without retreating into vocabulary you are expected to take on faith.
  • Prices by the hour with no outcome definition, no ninety-day picture, and no named decision rights.
  • References that attest to effort and likeability rather than to a metric that moved.

One question to end every interview

If you keep a single line from this page, keep this one: “Who owns the outcome after the recommendation?” Everything above is that question in five costumes. A consultant owns the report, an advisor owns the advice; the fractional role only earns its fee when the answer is “I do”, said by the person who will still be in the room when the consequences arrive.

Choosing wrong here is not a neutral miss. The wrong fractional costs you six months, the roadmap that stalled while you found out, and the harder conversation of unwinding them, while the decisions that prompted the hire keep landing unmade. If you are weighing candidates now, book a call and run the five checks on us live. You get a straight read on your shortlist in the same conversation, including the honest answer if the right choice is nobody at all.