Part-time CTO vs interim CTO: which do you need?

People use these titles interchangeably. They should not. The contract shape matters more than the label.

Fractional / part-time CTO

Ongoing leadership, typically one to a few days per week, on a monthly retainer. Best when you need steady direction without a full-time hire.

Interim CTO

Full-time (or near full-time) coverage for a fixed period — often while you recruit a permanent hire, or during a crisis. Higher intensity, shorter horizon.

If your need is ongoing but not urgent full-time coverage, fractional is usually the better fit.