Direct answer
A technical cofounder is a long-term owner. A fractional CTO is a paid senior operator who helps the founder make technical decisions now. For many AI startups, fractional CTO support is the bridge until the right permanent technical leader exists.
Technical cofounders are not interchangeable with consultants
A cofounder owns the company outcome and should shape product, recruiting, culture, architecture, fundraising, and customer learning for years. If that person exists, choose carefully. If not, do not freeze the company while waiting.
Where fractional CTO support fits
A fractional CTO can help define the MVP, review architecture, interview engineers, manage vendor quality, and prepare the founder to recruit a technical leader from a stronger position.
How to avoid the wrong equity decision
Giving equity to solve a 90-day technical uncertainty can become expensive. Paid CTO support can de-risk the early roadmap without pretending to be a permanent cofounder.