Fractional CTO Services for Startups and Product Companies
Fractional CTO services for founders and seed-stage teams: a senior engineering lead, on a monthly block of hours agreed in writing, who makes the architecture, vendor and roadmap decisions and answers the technical questions investors ask, until you can justify a full-time CTO. Founder-led, hands on, and never for equity.
What fractional CTO services actually cover
A fractional CTO is a senior technical leader who owns your technology decisions for part of each month instead of all of it. A company can need a CTO's judgment long before it can use a CTO's full week: a non-technical founder paying an agency, a seed-stage team of strong specialists with nobody owning the whole system, a company whose technical lead has just left. Our version is different because the role sits on top of a working engineering firm. inteRFace R&D is founder-led and senior-only, so the person making the call on your platform has shipped on that platform, and when a decision needs a schematic read or a firmware review, that work happens the same week.
Week to week
- Architecture and platform decisions: microcontroller family, radio, operating system or bare metal, cloud provider, app stack. Each one written down with its reasons, so the decision survives the person who made it.
- Build versus buy: a module or a custom board, a managed IoT service or a lean stack, an off-the-shelf app or your own. Compared in engineering hours and calendar time, not in opinions.
- Vendor and contract-manufacturer selection: a shortlist, the questions to ask, quotes compared on an identical scope, and a read of the technical exhibits before you sign. Commercial and legal terms stay with your counsel.
- Roadmap and milestones: EVT, DVT and PVT for hardware, release trains for software, with what each build is meant to prove and the hours behind it.
- Design and code review: schematics, layouts, firmware, cloud and app code from your contractors, agency or in-house engineers, reviewed by someone who has shipped the same kind of work.
- Technical hiring: honest role definitions, interview plans and offer calibration, alongside your recruiter. The detail is on our technical hiring page.
- Investor questions: the technical answers in your data room, the diligence call, and the written plan a lead investor expects.
- A weekly engineering meeting with a decision log and a risk register, so nothing important lives only in one person's head.
Who leads it
Our founder, Shahaf Baron, leads engineering and design direction on every client engagement. He is a Materials and Mechanical Engineer by training and a full-stack developer by practice, with 15+ years in R&D, embedded systems and industrial IoT, and he builds and runs software products of his own: ArduinoStudio, Embedded Academy and the free tools on this site.
When you need a fractional CTO, and when you do not
You need one when technical decisions are being made by whoever happens to be in the room: a non-technical founder with an agency or a few contractors, each optimizing their own piece and nobody accountable for the whole; a seed-stage team whose best firmware engineer is now also choosing the contract manufacturer and defending the schedule to the board; a company raising a round, where the first question after the demo is who owns the technology. And a company whose CTO has left: an interim CTO on a monthly block keeps the team moving while the search runs.
You do not need one when you already have a technical co-founder who has shipped a product like yours; then you need delivery capacity or a second opinion, and a scoped project is cheaper than a leadership retainer. Nor do you need one when the problem is a single deliverable: a board, a firmware feature, an app release. If a scoped project is the right answer, we say so on the first call and quote that instead.
Fractional CTO versus a full-time CTO or a technical co-founder
A full-time CTO is right once there is a team to lead every day. Getting there takes time: a senior hardware engineer in the Bay Area takes four to nine months to hire, and a CTO search is rarely quicker. One also expects a senior salary and a meaningful equity grant: right at that stage, premature for a company still finding its product.
A technical co-founder solves the same problem with a permanent choice and a large share of the company: the right trade when the person is the right person. When that search drags on and the product is waiting, a fractional CTO is the technical co-founder alternative that does not cost a cap-table decision: the role scales up during a build, down once an in-house lead is in place, and ends when you no longer need it.
CTO as a service is the same engagement under a different name. Look for someone who has shipped what you are building, reviews real work rather than slides, writes decisions down, and will help you hire their own replacement. The questions in our guide to vetting a hardware engineering firm apply to a fractional CTO almost unchanged.
How it combines with the delivery team
A CTO with no engineers behind them is an advisor. Here the role sits on a delivery bench: electronics, firmware, mechanical design and production through Hardware for Startups; SaaS platforms, web applications and companion apps through software development.
It runs in one of two ways. In the first, we lead and your people build: your contractors, agency or in-house engineers do the work, and we set direction, review it, unblock it and own the decisions. In the second, we lead and build: the CTO block covers direction, and the delivery work is quoted separately in engineering hours, with phases written down, so you always see what leadership costs and what delivery costs.
The trade-offs between an outside firm and an in-house team are laid out in our outsourcing guide. A fractional CTO for startups is usually the bridge between the two: outside leadership while the in-house team is small, then a planned handover once you hire.
Technical due diligence for investors and acquirers
For a fund or an acquirer, technical due diligence is an engineering read of a company's technology, delivered as a written report: whether the architecture matches the claims, whether the design files and source code are complete and build, how much depends on one person, where certification and manufacturing readiness stand, and the open technical risks ranked by what they would cost to retire. We give an engineering opinion, not investment advice; valuation stays with you. For founders, the same exercise before a raise gets the data room ready before the first question.
What you receive from a fractional CTO engagement
- A written technical strategy: architecture, platform and build-versus-buy decisions, each with its reasoning.
- A roadmap with milestones and the engineering hours behind each phase, in a form you can put in front of investors.
- A decision log and a risk register, kept current at the weekly meeting.
- Review notes on every schematic, layout, firmware release, cloud design or app build that crosses the desk.
- A vendor and contract-manufacturer shortlist, with quotes compared on an identical scope.
- Role definitions, interview plans and scorecards for every technical hire.
- Investor materials: the technical section of the deck, data-room answers and a diligence-ready summary.
- Everything in your repositories and your drive from day one. You keep 100% of the IP, and a mutual NDA is signed before the first technical conversation.
How a fractional CTO engagement is priced
Priced in engineering hours. A fractional CTO engagement is a monthly block of engineering hours, agreed in writing before it starts, and sized to the stage: a founder with one contractor needs a smaller block than a team heading into DVT. Delivery work beyond the block is quoted separately, with phases written down before any work starts, so leadership and delivery never blur into one invoice. No equity, and no placement fees when we help you hire.
Where we do fractional CTO work
We are based in Silicon Valley and work with teams across the United States, mostly remotely: the weekly meeting on video, reviews inside your repositories, vendor calls in Pacific hours that overlap Eastern afternoons, and in-person days in the Bay Area by arrangement when a bring-up or a factory visit needs someone in the room.
How it starts
A free 30-minute call first, then a bounded first step: a technical review of your existing designs, code, vendors and plan, with a written assessment and a proposed monthly block, quoted in writing before any work starts. The block then runs month to month and is re-sized as the company changes.
Book the free 30-minute call and bring the decision you are stuck on; the call is engineering, not sales. If you want a planning number before we talk, the free Project Cost Estimator gives a range in engineering hours in a few minutes.
Frequently Asked Questions
What do fractional CTO services include, and how is that different from an advisor?
A fractional CTO owns your technical decisions for an agreed block of hours each month: architecture and platform choices, build versus buy, vendor and contract-manufacturer selection, the roadmap, design and code review, technical hiring and investor questions, with a weekly meeting, a decision log and a risk register. An advisor gives opinions when asked. A fractional CTO is accountable for the outcome, reads the actual schematics and code, and writes the decisions down so they outlive the engagement.
Do you take equity, like most fractional CTO arrangements?
No, never. The engagement is a monthly block of engineering hours, agreed in writing before it starts, and nothing else: no equity in any form. You keep 100% of the company and 100% of the IP; every document, design file and line of code is yours from day one, and a mutual NDA is signed before the first technical conversation. We would rather be paid for engineering than own a slice of a company we are supposed to advise without bias.
Does a fractional CTO for a hardware startup work differently from one for a software company?
Yes. Hardware decisions are expensive to reverse, so the role matters more, not less. A hardware CTO has to choose the microcontroller family and the radio, decide when a dev kit becomes a custom board, plan EVT, DVT and PVT, pick a contract manufacturer and plan certification, and still own the firmware, the app and the cloud. We work in all of those disciplines, with 150+ products delivered, so the decisions are made by people who have lived with their consequences.
Our CTO just left. Can you step in as an interim CTO?
Yes. An interim CTO on a monthly block keeps the team moving while you run a proper search: a review of what is in flight, a decision log so nothing is lost, the vendor and investor relationships kept warm, and a clear read of the risks the departure exposed. We then help you define the full-time role, interview candidates alongside your recruiter, and hand over with the documentation in order. The goal is a clean exit, not a permanent seat.
How many hours a month does a fractional CTO take?
It depends on the stage, and the block is agreed in writing before it starts. A founder with one or two contractors needs a small block: the weekly meeting, reviews and the occasional vendor call. A team heading into a build or a raise needs a larger one, because reviews, hiring and diligence all land at once. The block is revisited as the company changes, so you are not paying for leadership you no longer need.
Will you help us hire a full-time CTO and hand over?
Yes, and it is part of the plan from the start. When the company is ready, we write the role honestly, help your recruiter screen, run the technical interviews, calibrate the offer level and plan the new CTO's first 90 days. Because every decision, review and risk has been written down along the way, the handover is a reading exercise rather than an archaeology project. A fractional CTO who cannot be replaced has not done the job.
Ready to talk specifics?
A 30-minute call with a senior engineer beats three rounds of email. Tell us what you're building.