What a Fractional CTO actually does
The full-time CTO at a Series A company makes architecture decisions, runs the engineering hiring loop, owns the on-call schedule, sets the technical roadmap, and writes some code when the team is overloaded. Fractional CTO does the same work — minus full-time presence — for companies that aren't ready for the $400K all-in cost of a full-time hire.
A real fractional CTO engagement looks like:
- Weekly 1:1 with the founder, monthly board-style technical update
- Architecture decisions documented as RFCs (not Slack threads that disappear)
- Hiring scorecards, take-home rubrics, technical final-round interviews
- Code review on the team's PRs
- Hands-on weeks when a critical build is behind
When you need one
You're past pre-seed, have 1–4 engineers, and don't have a CTO. Decisions are being deferred or made by committee. You're losing 2–4 weeks on each major architecture call. A real CTO would unblock you, but a $400K hire doesn't make sense yet.
When you don't need one
You have a working CTO. You're pre-product, with no engineers, and the right move is to engage a build shop for v1. You're at Series B+ and need a full-time owner.
What it costs
Reasonable range: $3K–$8K/month for 10–20 hours, $8K–$15K/month for 20–30 hours. Avoid anyone quoting flat retainers below $2K/month (you'll get attention scraps) or above $20K (over-engineered for the role).
Versus engaging a build shop
A build shop ships product. A fractional CTO unblocks decisions and develops your team. For the first build, engage the shop. For ongoing technical leadership with an existing team, hire the fractional CTO. Sometimes both — the same person can wear both hats for 1–2 months during a transition.