What does a fractional CTO actually do?
The short answer
A fractional CTO is a senior engineer who takes technical responsibility for a company part-time, usually a few days a month on a rolling retainer. They review what the existing developers ship, set engineering standards in writing, translate technical decisions into commercial consequences, and interview technical hires. They do not write production code.
The definition, without the consulting fog
A fractional CTO holds the technical responsibility a full-time CTO would hold, for a fraction of the time and cost, on a rolling arrangement. In practice that is two to five days a month for somewhere between $4,000 and $12,000, depending on seniority and involvement.
The word doing the work in that sentence is responsibility. A consultant advises and leaves; the recommendation's consequences are yours. A fractional CTO stays, and the consequences of their judgement land on them month after month. That difference changes the advice you get.
The four things the role is actually for
Every genuine fractional CTO engagement we have seen reduces to some mix of these. If a proposal does not describe at least two, it is a consultant with a better title.
- 01Review. Someone senior reads what your developers ship, before it is in production rather than after an incident. This is the largest share of the time and the reason the role exists.
- 02Standards. Definition of done, code review rules, release process and on-call expectations, written down and agreed with the team rather than imposed on it. A standard nobody accepted is not a standard.
- 03Translation. Turning technical decisions into commercial consequences in both directions, so your board hears risk in money and your developers hear priorities in outcomes.
- 04Hiring. Running the technical interview, evaluating candidates and agencies, and telling you when a CV is stronger than the person.
What it is not
- Not a developer. If someone bills as a fractional CTO and spends the retainer writing features, you are paying a premium rate for a contractor and getting no oversight.
- Not a project manager. They set the technical standard; delivery scheduling stays with whoever runs the roadmap.
- Not your team's line manager. They review the work and report on it; the employment relationship stays yours.
- Not on-call. Operating the system day to day belongs to whoever runs it.
When you need one
The clearest signal is a specific discomfort: your developers are shipping and you have no way to tell whether the work is good. Everything else is a variation on that.
- You have engineers, freelance or in-house, and nobody senior reviewing their decisions.
- Your agency is the only party who understands your own system.
- Estimates keep slipping and you have no independent read on why.
- You are about to hire developers and nobody on your side can interview them.
- An investor or acquirer has started asking technical questions you cannot answer.
When you do not
Four situations where the honest answer is that a retainer would waste your money.
| Your situation | What you actually need |
|---|---|
| No developers yet, one build to commission | A one-off consulting session and a written scope |
| One specific decision blocking you | A consulting session, not a monthly commitment |
| A single question about work already delivered | A code audit, which answers it with evidence in days |
| A strong senior engineer already leading well | Nothing. Do not add a layer above someone doing the job |
How to tell whether it is working
The role produces mostly invisible output, which makes it easy to keep paying for nothing. Three months in, you should be able to point at concrete artefacts.
- A written engineering standard your team follows and can quote back to you.
- Monthly written reports on delivery health and technical risk, including things you did not want to hear.
- At least one problem caught in review that would have been expensive in production.
- Your own improved ability to ask your developers the right question, which is the compounding benefit.
If three months have produced none of those, the arrangement is not working, and a rolling monthly agreement exists precisely so you can end it.