A fractional CTO is an experienced technology leader who makes a company’s technical decisions for a set number of hours or days each month. The arrangement is shared across a few clients and usually paid by retainer. Some providers call it a part-time CTO or CTO-as-a-service. An interim CTO is a full-time leader placed for a few months, typically after a departure.
The most common buyer is a founder who does not write code and has a product that someone else built.
What a fractional CTO owns
At a $1M to $100M company, the role covers six areas.
Architecture. How the system is built, where it runs and whether it will hold up at five times today’s usage. This includes the cloud bill, which a fractional CTO often cuts in the first quarter.
Build versus buy. Whether to write software, license it or stitch together existing tools. Founders who have just raised money tend to build too much.
The team or the vendor. Hiring and managing in-house engineers, or directing an outside development shop, including reviewing its estimates and its work.
Code ownership. Making sure the company owns its source code and accounts: the repository, the cloud account, the domain, the app store listings. Agencies sometimes hold these, which becomes a problem when the relationship ends.
Security basics. Access control, backups, dependency updates, and answers to the security questions customers ask. Formal compliance work such as SOC 2 often moves to a fractional CISO.
Due diligence. Preparing for an investor’s or buyer’s technical review, or conducting one on a company you plan to acquire.
Hours and fees
Fractional CTO time ranges widely. Advisory arrangements run 4 to 20 hours a month. Embedded roles run up to two days a week. Published fees follow the same spread: from about $3,000 a month for on-call advice to around $15,000 for an embedded role, and $100 to $250 an hour on talent marketplaces. Many work month-to-month. The cost guide has the details.
When to hire one
The usual triggers: a non-technical founder needs someone to judge the agency or freelancers building the product; the product works but slows down or breaks as customers grow; the company is about to hire its first senior engineers and nobody can interview them; investors or a buyer have scheduled technical due diligence; or the founder suspects the development budget is being wasted and cannot prove it.
Who it is not for
A company whose product is a configured off-the-shelf tool, such as a Shopify store with apps, usually needs a good developer or agency, because a CTO would have too little to decide. A software company with ten or more engineers needs a full-time technical leader in the team every day. And a company that mainly wants to automate internal work with AI tools may be better served by a fractional Chief AI Officer, whose focus is operations across the company.
Independent CTOs and agency CTOs
Many development agencies sell a fractional CTO alongside their build services. That can be convenient, and the CTO may know the codebase well. But a CTO employed by the vendor cannot judge the vendor independently. If your main need is oversight of an outside development team, hire an independent fractional CTO.