A comparison of the three ways to get technical leadership, with the situations where each one fits and where it does not.
In short
CTO as a service, also called a fractional CTO, gives you senior technical leadership part-time on an ongoing basis. An interim CTO fills the full role for a limited period. Choose fractional for direction, architecture and hiring support without a full-time executive; choose interim when the seat is empty and needs someone every day.
Most growing companies reach a point where technical decisions are too important to leave to whoever happens to be the most senior developer, but where a full-time CTO is not yet justified or not yet found. This comparison is written by Devies, a Gothenburg-based product and engineering consultancy, for CEOs, founders and boards deciding how to fill that gap. It covers the models, what each costs in time and accountability, and how to choose.
What is the difference between an interim CTO and CTO as a service?
An interim CTO is an experienced technology executive who takes on the full CTO role for a limited period, while CTO as a service is a part-time arrangement where a senior technology leader works with you a set number of days or hours over a longer period. Both are ways of buying leadership rather than hiring it permanently.
Three definitions keep the comparison precise:
- A CTO (Chief Technology Officer) is the person accountable for technology strategy, architecture, the engineering organisation and technical risk, and who represents technology in the management team and towards the board.
- An interim CTO is a temporary, usually full-time holder of that role, brought in to bridge a vacancy, lead a turnaround or carry a specific change such as a platform migration.
- A fractional CTO, sold as CTO as a service, is a senior leader who covers the essential parts of the role part-time, often alongside other clients, with a long-term horizon.
Both differ from hiring IT consultants (IT-konsulter) to build software. A consultant developer adds capacity to the team; a CTO, interim or fractional, takes responsibility for direction and decisions. If you are still deciding how to buy development capacity itself, our comparison of IT consultants, development teams and project delivery covers that choice.
How do the options compare?
The options differ mainly in how much time you get, how embedded the person is and how continuity is handled when they leave. The table compares them on the criteria that usually decide the question.
Criterion
CTO as a service
Interim CTO
Permanent CTO
Time commitment
CTO as a service
Part-time, for example a few days a month
Interim CTO
Full-time or close to it
Permanent CTO
Full-time
Typical horizon
CTO as a service
Ongoing, months to years
Interim CTO
Fixed period, often until a hire or a milestone
Permanent CTO
Open-ended
Main purpose
CTO as a service
Direction, architecture, hiring and governance without a full-time executive
Interim CTO
Fill an empty seat, lead a turnaround or a large change
Permanent CTO
Own technology long term
Presence in daily work
CTO as a service
Limited, focused on decisions and coaching
Interim CTO
High, manages the team day to day
Permanent CTO
High
Cost profile
CTO as a service
Lowest total cost, predictable fee
Interim CTO
High for a limited period
Permanent CTO
Salary, benefits and recruitment cost
Speed to start
CTO as a service
Fast
Interim CTO
Fast to medium
Permanent CTO
Slow, recruitment takes months
Continuity risk
CTO as a service
Knowledge sits with an external person unless documented
Interim CTO
High at handover when the period ends
Permanent CTO
Lowest, if the person stays
Best for
CTO as a service
Start-ups, scale-ups and companies without in-house tech leadership
Interim CTO
Companies between CTOs or in a critical change
Permanent CTO
Companies where technology is the core business at scale
Choose CTO as a service when
- you need someone senior to set technical direction, review architecture and challenge suppliers, but there is not enough leadership work for a full-time role;
- your development is partly or wholly outsourced and you need someone on your side of the table when outsourcing IT work;
- you are preparing for an investment round or an acquisition and need a technical due diligence perspective;
- your senior developers need mentoring and a clear roadmap more than they need a manager.
Choose an interim CTO when
- your CTO has left and teams, suppliers and budgets need a decision-maker every day;
- a large change, such as a platform replacement or a merger of two engineering teams, needs full-time leadership for its duration;
- the board wants a stable leader in place while it recruits a permanent CTO.
When does a fractional CTO make sense?
A fractional CTO makes sense when the company needs senior technical judgement on a regular basis, but the volume of leadership work is a fraction of a full-time role. That is often the case for companies with one or two development teams, a product built largely by suppliers, or a non-technical founder.
Typical signals that it is time:
- Technical decisions are made by default. Architecture, tools and suppliers are chosen by whoever is closest to the problem, and nobody weighs them against the business plan.
- The board or investors ask questions nobody can answer. Security posture, scalability and technical debt come up, and the answers are guesses.
- Hiring stalls. You cannot assess senior candidates, or good developers leave because there is no technical career path.
- Supplier dependence grows. You rely on a consultancy or platform vendor and have no independent view of whether its proposals are right.
- Regulation reaches technology. Rules such as NIS2 put cybersecurity on the management agenda, and someone has to translate them into technical priorities.
On the last point, the NIS2 directive (EU) 2022/2555 says in Article 20 that management bodies of covered entities must approve cybersecurity risk-management measures and oversee their implementation. As of October 2026, Sweden has implemented the directive through the Cybersecurity Act (cybersäkerhetslagen, SFS 2025:1506), in force since 15 January 2026. A fractional CTO can prepare those decisions, but accountability stays with the management body.
What should you agree before you start?
Agree scope, decision rights and the exit before the first day, because a part-time or temporary leader can only be effective if everyone knows what they own. Most problems with both models come from unclear mandates rather than from the person.
Put these points in writing:
- Mandate. Which decisions the CTO makes, which they recommend, and to whom they report.
- Time and availability. Days per month, response times and who covers urgent incidents.
- Outcomes for the first 90 days. For example a technology roadmap, an architecture review or a hiring plan.
- Documentation and handover. Decisions, architecture and supplier agreements recorded where the company owns them, so knowledge stays when the person leaves.
- Employment form. An interim CTO can be hired on a fixed-term basis or contracted through a company. Under the Swedish Employment Protection Act (lagen om anställningsskydd, 1982:80), as of October 2026 a special fixed-term employment turns into a permanent one after more than twelve months with the same employer within a five-year period. Check the arrangement with an employment law adviser.
Devies
Want a second opinion?
Devies, a Gothenburg-based product and engineering consultancy, works on questions like this with Nordic product and IT teams. Tell us where you are and we will suggest a sensible first step.
Frequently asked questions
What does a fractional CTO do?
A fractional CTO sets technical direction, reviews architecture, helps hire and mentor developers, assesses suppliers and represents technology towards management, the board and investors. They work part-time, often a few days a month, and focus on decisions and coaching rather than daily team management. The aim is senior judgement where it matters most, without the cost of a full-time executive.
How long should an interim CTO stay?
An interim CTO usually stays until a defined milestone: a permanent CTO is in place, a turnaround is complete or a major change has been delivered. Agree that milestone and a handover plan at the start. If the assignment is a fixed-term employment in Sweden, remember that a special fixed-term employment turns permanent after more than twelve months within five years with the same employer.
Can a fractional CTO become a full-time CTO later?
Yes, if both sides want it, but plan for it rather than assume it. Many companies use a fractional CTO to set direction and build the team, then recruit a permanent CTO once technology leadership needs a full-time person. The fractional CTO can help write the role, assess candidates and hand over, which reduces the risk of a costly wrong hire.
Is CTO as a service the same as outsourcing IT?
No. Outsourcing IT means handing over the delivery or operation of systems to a supplier. CTO as a service gives you a senior leader who works on your side, setting direction and holding suppliers to account. The two often go together: a company that outsources development benefits from an independent technical leader who can judge whether the supplier's proposals and quality are right.
