Fractional CTO services for pre-seed to Series A startups.
Mayur Kale is a hands-on Fractional CTO in London working with pre-seed to Series A startups and scale-ups across the UK. He owns technology strategy, product, engineering, and delivery end-to-end — writing production code, leading the team, and reporting to the board — without the £150k–£200k cost of a full-time CTO.
What is a Fractional CTO?
A Fractional CTO is a senior engineering leader who owns a startup's technical direction on a part-time basis — typically one to two days a week. It gives founders the same accountability as a full-time CTO — architecture, hiring, and a technical voice for the board and investors — at a fraction of the cost.
Unlike a technical advisor, who offers a few hours of guidance, or a consultant, who delivers a scoped project and leaves, a Fractional CTO is embedded and accountable for outcomes. Mayur Kale doesn't just advise — he builds, hires, and ships alongside the team.
It also differs from an interim CTO, who covers the role full-time for a limited period (often during a search or transition), and from a virtual CTO, which usually means fully remote, advisory-only support. A Fractional CTO gives you permanent, part-time technology leadership — the strategy and the hands-on delivery, week in, week out.
What makes a good Fractional CTO
Anyone can put "Fractional CTO" on a LinkedIn profile. Whether you hire me or someone else, these are the qualities to vet for — and how I stack up against each one.
Still hands-on in the codebase
An advisor who stopped coding years ago will hand you strategy they never have to live with. Ask when they last shipped to production. My answer: this week — I ship in Java, TypeScript, Node, Python, and Solidity on every engagement.
Fluent with boards and investors
The role is half translation: architecture into language a board and an investment committee can act on. I've sat in board rooms explaining technical decisions to non-technical founders and investors, and run fundraising workstreams from the inside.
Proven hiring judgment
Your first five engineers define your velocity for two years, and the wrong profile costs you year one. A good Fractional CTO has hired, fired, and mentored engineers — and runs the loops with you rather than reviewing CVs from a distance.
Architecture matched to your stage
Two failure modes: architecture that collapses at 10,000 users, and over-engineering that burns runway on scale you don't have. The judgment is knowing which risk you're actually facing — that comes from having built at both ends, pre-seed to national-scale platforms.
Breadth beyond pure software
Startups don't have neat problems. The same week can span product prioritisation, a data pipeline, a security review, and an AI feature. I cover product, engineering, data, security, and AI/ML rather than handing half the job back to you.
Honest about fit — including bad fit
The tell of a good Fractional CTO is what they turn down. I only work with a handful of clients at any given time, and if you're post-Series B and need someone full-time, I'll say so on the discovery call rather than sell you the wrong model.
The situations where founders call me
If one of these sounds like your next quarter, that's usually the moment a Fractional CTO pays for itself.
A raise is weeks away
Investors will diligence your stack, your team, and your roadmap — and they expect a technical counterparty in the room. I get the technical story credible and sit on your side of the table through DD and deal mechanics.
You're a non-technical founder deciding alone
Every agency quote, every architecture choice, every 'trust me' from a contractor lands on you with no way to judge it. I become the senior technical voice that owns those calls — and is accountable for them.
The first engineering hires are about to happen
Whoever you hire first sets your velocity for the next two years. I define the profiles, run the loops, and make sure you don't pay for the wrong first hire in year one.
The prototype now has to become a product
A founder-built demo has real users or design partners, and the next step is production software. That's exactly the Bidwise AI engagement: prototype to production platform, founding team hired, pre-seed closed.
The architecture is starting to creak
What worked for 100 users is breaking at 10,000, and every fix spawns two more. I read the code, decide what genuinely needs rebuilding, and stage the fix so shipping never stops for a six-month rewrite.
Someone needs your stack diligenced
An investor commissioned technical due diligence — or you want your own house checked before they do. Fixed fee, 5–7 day turnaround, written report ready for investment committee.
30 minutes, free, and an honest read on fit — not a pitch.
Engagement models & day rates
Fractional CTO day rates in the UK typically run £800–£1,500, with London at the top of that range — against a £150k–£200k+ all-in cost for a full-time hire. I quote per engagement after a free discovery call; every model below runs on a fixed monthly retainer with a 30-day notice period.
Embedded retainer
The core model: 1–2 days per week as your part-time CTO. Technology strategy, architecture, hiring, and board reporting — plus production code every week. Best for pre-seed to Series A teams building toward a raise.
Technical due diligence
Fixed-fee, 5–7 day turnaround. A written report on the technology stack, team, and delivery risk — ready for an investment committee, or for founders preparing to be diligenced.
Advisory & fundraising support
Lighter-touch technology leadership for founders who need a senior counterparty: architecture reviews, hiring loops, investor materials, and fundraising workstreams — scaled up or down as the round demands.
What I do as your Fractional CTO
Senior technical leadership across the areas a scaling startup actually needs — owned, not just advised on. Hands-on means hands-on: code review, architecture, and shipping alongside your team.
Fractional CTO Leadership
Embedded as your part-time CTO. Own technical direction, unblock the team, run fundraising and hiring workstreams, and report into the board.
Production Engineering
Fully-complete, production-grade solutions — not prototypes. Architecture, full-stack build, data and AI, infrastructure, and delivery, owned end to end by one accountable engineer.
Security & Compliance
Get certified, not just "ready". Cyber Essentials, Cyber Essentials Plus, ISO 27001, and ISO/IEC 42001 for AI systems — taken through to the certificate, with continuous monitoring via Sprinto cutting months off the timeline.
Who I work with
I work with pre-seed to Series A startups, usually with 2–15 engineers — or none hired yet. The fit is strongest when the founder isn't deeply technical, a fundraise is on the horizon, or the first engineering hires are about to define velocity for the next two years. If you're post-Series B and need someone in the building full-time, I'll tell you on the call.
Recent work
A sample of what "hands-on" looks like in practice.
Bidwise AI
AI eSourcing platform for UK public-sector procurement — prototype to production, founding team hired, pre-seed closed.
Global electronics & healthcare manufacturer
Explainable inventory-allocation engine — a transparent linear program that splits factory output across distribution centers at lowest landed cost.
Satellite company
Corporate + investor-relations website — CMS-driven, internationalized across 10 locales, with 3D/WebGL brand experiences.
A specialist for hard enterprise problems
Not every engagement is a Fractional CTO role. Larger companies and Fortune 500 enterprises bring me in as the specialist on a specific, high-stakes problem — from an explainable supply-chain optimization engine to a data platform or a production AI/ML feature. Deep in software engineering, data engineering, and AI/ML — hands-on, and accountable for shipping the thing that actually works.
Frequently asked.
What does a Fractional CTO actually do?
A Fractional CTO is a senior engineering leader who owns your technical direction part-time. In practice I set architecture and the technical roadmap, lead and hire the engineering team, act as the technical counterparty for the board and investors, and stay hands-on in the codebase. It's the same accountability as a full-time CTO — outcomes, not hours — at 1–2 days per week. I work with pre-seed to Series A startups.
How much does a Fractional CTO cost in London?
London day rates sit at the top of the UK range — typically £1,000–£1,500 per day, or roughly £4k–£12k per month depending on days per week and scope. That's still a fraction of the £150k–£200k+ all-in cost of hiring a full-time CTO in London. I quote per engagement after a free discovery call, based on stage, scope, and hours.
Do you work on-site in London?
Yes. I'm based on Paul Street in Shoreditch — the heart of London's tech scene, minutes from Old Street roundabout — so for London startups I'm in the room for workshops, kickoffs, board meetings, and critical hires — and remote the rest of the week. Outside London I work remote-first across the UK and travel where it matters.
How much does a Fractional CTO cost in the UK?
Fractional CTOs in the UK typically run from roughly £800–£1,500 per day, or £4k–£12k per month depending on days per week and scope — a fraction of the £150k–£200k+ all-in cost of a full-time CTO. I don't publish a fixed rate because it depends on stage, scope, and hours; the discovery call is free and I quote on the follow-up.
When should a startup hire a Fractional CTO instead of a full-time one?
Hire fractional when you need senior technical leadership — architecture, hiring, a technical voice for investors — but can't yet justify or afford a full-time CTO. That's most pre-seed to Series A startups. It's ideal when you have 2–15 engineers (or none yet), a founder who isn't deeply technical, or a raise coming up. Once you're post-Series B and need someone in the building full-time, a Fractional CTO is the wrong fit and I'll tell you so.
What's the difference between a Fractional CTO and a technical advisor or consultant?
An advisor gives you a few hours a month of guidance and takes no ownership. A consultant delivers a scoped project and leaves. A Fractional CTO is embedded and accountable: I own technical decisions, run the team, write production code, and report to the board — I don't just advise, I build. That ownership is the difference.
Do Fractional CTOs write code?
I do — every week. Writing production code keeps the strategy honest: every architectural call I make, I'm also accountable for living with as a contributor on the same codebase. I ship in Java, TypeScript, Node, Python, and Solidity, and pair with the team on the hard problems.
How many clients do you take on at once?
Deliberately few. I only work with a handful of clients at any given time so every client gets real attention — not someone splitting their calendar eight ways. Current availability: 2 engagement slots left this quarter. Once the slots are filled, the next opening is typically 60–90 days out, so if you're weighing a call, book it now rather than later.
How does a Fractional CTO engagement work?
I embed with your team 1–2 days per week on a fixed monthly retainer. You get senior technical leadership for a fraction of a full-time CTO's cost — typically £80k–150k saved annually.
What stage companies do you work with?
Pre-seed to Series A. Usually 2–15 engineers. If you're post-Series B and need someone full-time, I'll tell you on the discovery call.
Do you publish pricing?
I publish ranges rather than a rate card: UK Fractional CTO day rates typically run £800–£1,500, with London at the top of that range. The exact quote depends on scope, stage, and days per week — the discovery call is free and I quote on the follow-up.
Are you remote or on-site?
Remote-first, UK-based. I travel on-site for workshops, kickoffs, board meetings, critical hires, and any other moment where being in the room actually matters. Expenses billed at cost.
Who owns the IP of work you produce?
You do. Standard work-for-hire terms in every engagement contract — no ambiguity, no IP carve-outs.
What's the notice period?
30 days either side after the initial 2-week assessment. No long tie-ins.
Can you do one-off technical due diligence?
Yes. 5–7 day turnaround, fixed fee, written report ready for investment committee.
Do you help founders raise?
Yes — I've run full pre-seed fundraising with founders from the inside. Contracts (SeedLegals), financial modelling, investor DD, and deal negotiation. Not as a placement agent or introducer: as the technical co-founder-equivalent who owns the workstream alongside you.
Ready to scale your engineering?
Book a 30-minute discovery call. If we're not a fit, I'll tell you on the call — and point you toward someone who is.