What a fractional CTO does, and when a startup should hire one

Zayin Krige, 2023-11-15. 4 min read.

A fractional CTO is an experienced engineering leader who works for a company part-time, typically one to three days a week, and takes ownership of technical strategy, architecture, hiring and delivery. The company gets senior technical leadership without the salary, equity and notice period of a full-time chief technology officer. The arrangement suits companies with between zero and roughly fifteen engineers that need direction more than they need another pair of hands.

What does a fractional CTO do?

The title varies, the work does not. Across the engagements I have run through Apex Technology since 2001, a fractional CTO engagement covers five things.

1. Architecture decisions. Choosing the stack, the hosting model and the boundaries between systems, and writing those decisions down so the next developer does not relitigate them.
2. Hiring and managing developers. Writing the job spec, running the technical interview, setting the standards a pull request is held to, and telling a founder plainly when a hire is not working.
3. Delivery ownership. Turning a business priority into a shipped release with a date attached, and being the person accountable when the date moves.
4. Vendor and cost control. Cloud bills, SaaS subscriptions, outsourced teams. Someone has to read the AWS invoice line by line.
5. Technical due diligence. For a raise, an acquisition or a partnership, an investor wants a credible technical person across the table. A fractional CTO is that person.

When it makes sense

Three situations come up repeatedly.

A non-technical founder with an outsourced build

The agency delivers on time and the founder has no way to judge whether what was delivered is any good. A fractional CTO reads the code, checks the infrastructure and negotiates with the agency from a position of knowledge. This is the most common reason I am hired.

A small team that has outgrown its first architecture

The prototype that won the first customers is now a liability: one database, one server, no tests, one developer who understands it. The team needs a migration plan that does not stop feature work. On a health-data platform I architected the move to an event-driven serverless design on AWS, which grew to more than 90 Lambda functions wired with SNS, SQS and DynamoDB, while the product kept shipping.

A regulated build that cannot afford a wrong turn

Insurance, lending, health data and identity all carry compliance obligations that a generalist developer will not know about until an auditor asks. On a lending platform with month-end general-ledger exports and NLR (National Loans Register) reporting, the architecture had to be right the first time.

When it does not make sense

• You have more than fifteen engineers. At that size the role is full-time and the company should hire for it.
• You need someone writing code forty hours a week. That is a senior contract developer, which is a different and cheaper engagement.
• You want a name on the pitch deck and nothing else. Investors check, and a fractional CTO who has not seen the codebase cannot answer their questions.

What it costs

A fractional CTO is billed as a day rate or a monthly retainer for a fixed number of days. Two days a week costs roughly forty percent of a full-time CTO's salary with no equity, no benefits and no notice period beyond the contract's termination clause. Rates vary widely by market.

What to ask before signing

1. Have you built and run a production system yourself, recently? Slide-deck architects are common. Ask for a system they built from zero and still operate.
2. Have you hired and let go of developers? Hiring is the part of the job most people underestimate.
3. What will you write down? The deliverable of a fractional CTO is decisions on paper: an architecture document, a hiring plan, a roadmap with dates. If the answer is "I will be in Slack", keep looking.
4. How many other clients do you have? Two or three concurrent engagements is normal. Six is a problem.
5. Who owns the code and the accounts? The company does, always. Every cloud account, domain and repository must be in the company's name from day one.

How I run the engagement

The first two weeks are an audit: code, infrastructure, cloud bill, team. The output is a written report with the three things to fix first. After that it is a fixed number of days a week with a standing weekly session with the founder, and I stay hands-on in the codebase because a CTO who cannot review a pull request cannot hold a team to a standard.