Walsh London · Senior Software, AI & Fractional CTO Consultancy

Selected Outcomes

Receipts from
recent engagements

Metrics from shipped client work, not internal estimates. References and case detail available on request.

12 weeks iOS + Android, zero to launch Built a full cross-platform e-commerce app from scratch. Basket, shipping and payments via Stripe, Apple Pay, and Google Pay. Cosmetify

93 days MVP to live Delivered a mobile pilot for EDF Energy's new-energy initiative in 93 days, setting a new bar for time-to-market. EDF Energy · via Contino

4.1★ Store rating climb Reworked performance and UX on a legacy mobile app, driving store rating from 3.2 to 4.1 stars across 25k+ reviews. Fantastec

50k+ Users per app Shipped iOS and Android apps for Money2020 Asia, Money2020 Europe, and Cannes Lions on tight 3–4 month windows. Ascential

2 yrs Fractional CTO engagement Ongoing fractional CTO role. Technical strategy, architecture, and hiring across a multi-year engagement. Multi Task Software

5× App speed boost Increased app load and API response times fivefold across iOS and Android, measured end-to-end. Fantastec

Selected Work

Clients who trust us

B2B SaaS · Telecoms · CTO Advisory

MultiTask

Walsh London was brought in as the senior technology leader to stabilise and professionalise a telecoms CRM platform being repositioned as a standalone B2B SaaS product. This meant leading a complex agency transition, diagnosing legacy technical debt, resetting engineering governance, and overseeing a migration to AWS, giving the business a credible foundation to scale from.

View MultiTask →

Football · Blockchain · NFT

Fantastec Swap

Fantastec's managing partner approached Walsh London directly to rescue their slow, bug-ridden licensed football NFT app. After a thorough scoping phase, we rebuilt the entire platform from scratch, delivering a high-performance, stable product that their user base had long been waiting for.

Engagement completed · Company subsequently closed

Energy · Enterprise · Zero Carbon

EDF Energy

Walsh London delivered EDF's pilot app from scratch in just 93 days. We were retained post-launch to advise on mobile team recruitment, upskilling, and the second version, alongside ongoing consultancy on agile development practices and engineering culture at one of the UK's largest energy companies.

View EDF Energy →

Aviation · Training · EdTech

Silicon Sky · AvA

Silicon Sky brought Walsh London in to completely rebuild their legacy Radio-Telephony training app after the original developers fell short. After months of close collaboration and beta testing with real pilots, AvA now helps aviators at every level master radio communications with confidence.

View Silicon Sky →

E-Commerce · Beauty · Cross-Platform

Cosmetify

Cosmetify exclusively engaged Walsh London to build their mobile app from scratch, iOS and Android in full parity, within a 12-week deadline. We delivered on Halloween 2020 as committed, with weekly demos and agile coaching throughout. The app launched to strong reviews and remains live on both stores.

View on App Store →

HR Tech · Employee Benefits · Enterprise

Perkbox

Walsh London was engaged to contribute to mobile development on Perkbox's employee benefits and wellbeing platform, one of the UK's most widely used HR tech products, serving thousands of businesses and their workforces. Work spanned cross-platform mobile, feature delivery, and technical collaboration with their engineering team.

View Perkbox →

What We Do

Our services

All projects are scoped on a case by case basis.

◆

Web & Mobile Development

React, React Native, iOS & Android
Payments, subscriptions & IAP
Maps, camera, biometrics, push
Offline-first & real-time sync
Performance & App Store delivery

Full native stack available on request

◆

Fractional CTO & Leadership

Technical strategy & roadmap ownership
Engineering hiring & team building
Architecture & code review
DORA-informed delivery metrics
Board & stakeholder communication

Two days a week, three-month minimum

◆

AI & Intelligent Features

LLM integration (OpenAI, Claude, Gemini)
In-app chat, agents & assistants
RAG & vector search
Voice AI & computer vision
AI feature strategy & guardrails

On-device ML, fine-tuning and more

◆

Cloud, DevOps & Architecture

AWS, GCP, Firebase & Supabase
CI/CD (GitHub Actions, Bitrise, EAS)
Terraform & infrastructure-as-code
API design & database work
Monitoring, Sentry & alerting

Full release automation included

How We Work

A process built for
delivery

Discovery

We scope your project thoroughly, understanding goals, users, constraints, and technical landscape before a line of code is written.

Design & Plan

Architecture decisions, sprint planning, and milestone alignment. We involve you in every meaningful decision from the start.

Build & Iterate

Weekly demos, constant communication, and agile cycles keep the build on track. We use the latest AI-assisted development tooling to move faster without cutting corners.

Deploy & Support

From App Store submission to production pipelines, we handle every step of the release, and remain available post-launch.

About Walsh London

We are doers,
not talkers

Most consultancies promise the world and hand you a project manager. Walsh London does the opposite: senior engineering and consulting, delivered directly by the people who will write the code.

Work spans mobile apps, cloud infrastructure, and AI integration, for founders through to enterprise teams. Clear scope, realistic timelines, and the honest version of what it will take.

Modern tooling, including AI-assisted development, means faster delivery and leaner builds. Less overhead, more working software.

Plain English

Tech explained the way you'd explain it to a friend. Before we quote you anything, we'll tell you if building the thing is actually the right call.

Direct Delivery

No account managers, no hand-offs, no ticket queues. The person you speak to is the person writing the code and making the technical calls.

Fair Pricing

Fixed scopes where they fit, flexible scopes where they don't. You'll always know what we're working on this week and exactly what you're paying for it.

Who we work with

Solo founderswith an idea and a budget, needing someone to turn it into a real product.

Small businesseswho need honest advice on what to build, how much it should cost, and whether it's worth it.

Scale-upsneeding senior engineering leadership, fractional CTO support, or a trusted second opinion.

Enterpriseswith a specific, scoped problem that benefits from outside hands, not a twelve-person team.

Led by

Charles Walsh

Founder and lead consultant of Walsh London. Twelve years shipping software across web, mobile, cloud and AI, from hands-on engineering through to fractional CTO roles. Clients include Ascential, EDF Energy (via Contino), Cosmetify, Perkbox, Fantastec and Multi Task.

Before that, I spent four years co-founding World Confections UK with my father. A multi-million pound import and distribution business built from scratch, which gave me a commercial grounding that still informs every technical decision I make today.

How I work

Direct delivery. Senior hands at the keyboard from first call to last commit
Fractional CTO & tech leadership for founders, startups and scale-ups
AI-native product work. LLM features, agents, RAG and AI-assisted development
React / React Native across iOS, Android and web
Clear scope, honest advice, and the truth when something won't work

Start a Project →

Selected Experience

A career built on
shipping

2025 – Present

Founder & Principal Consultant

Walsh London Ltd

Continuing the consulting practice under a new entity, repositioned & rebranded for AI-era

2018 – 2025

Founder & Principal Consultant

Walsh Enterprises Ltd

Selected client engagements

2023 – 2025 Fractional CTO · Multi Task Software

2021 – 2023 Engineering Manager · Fantastec

2019 – 2022 Mobile & Lead Consultant · Cosmetify, EDF Energy (via Contino), Perkbox

2017 – 2018

Lead Product Developer

Ascential

Nominated for Business Partner Rising Star, 2018 Ascential Excellence Awards

2015 – 2017

Software Developer

Kantar

2011 – 2015

Co-Founder, COO & Director

World Confections UK

Client Feedback

Words from those
we've worked with

Walsh London's depth of mobile expertise accelerated our development significantly. We set an ambitious deadline that felt almost unreachable. They delivered everything on time and to an exceptionally high standard.

Miles CTO · Cosmetify

Walsh London worked collaboratively with our team to help navigate the pioneering digital collectibles sector, providing technically excellent solutions with real-world clarity. An experienced, senior voice that bridged the gap between our customers and product team seamlessly. We would not hesitate to recommend them for any assignment of similar calibre.

Steve Co-Founder & CEO · Fantastec

It was fantastic having Walsh London on the team. Seeing a new feature demoed on day three of the engagement was genuinely impressive. A great team player and a very talented engineering partner. Highly recommended to any team.

Brendan CTO · Contino (EDF Energy engagement)

After inheriting a significant amount of tech debt from a previous agency, Walsh London's calm approach and ability to ship quickly started speaking for itself immediately. Weekly demos came thick and fast, and features we'd never managed to get working previously arrived like clockwork. A genuine pleasure to work with. They'll be the first call we make when we secure our next round.

Kirk CEO · Silicon Sky

Packaged Engagements

Clear scope,
clear pricing

Three standard engagements with fixed scopes and known costs, so you can see yourself in the work before a single call.

Every engagement is scoped on a call first. These are starting points, not fixed quotes. All prices shown are exclusive of VAT where applicable.

Discovery Sprint

Find out what to build

£4,000 2 weeks

For anyone who isn't sure what to build yet. You leave with a written delivery plan, a working technical shell, and a straight answer on whether building it is worth your money.

User and problem discovery
Wireframes, user flows & system design
Costed delivery roadmap (phased)
Go / no-go recommendation

Start discovery →

MVP Kickstart · Fixed Scope

Ship your first product

from£25,000 12 weeks

Your product in real users' hands inside a quarter. Web app, mobile app, SaaS platform, or all three. Weekly demos, agile delivery, full code handover.

Web, iOS & Android (React & React Native)
Custom SaaS platforms & APIs
Production infrastructure on AWS or Firebase
App Store, Play Store & web deployment
Weekly demo cadence, full code handover

Kickstart your MVP →

Fractional CTO

Senior leadership on tap

from£5,000 per month

For funded startups and scale-ups that need a senior technical voice without a full-time CTO hire. Two days a week, three-month minimum. Long enough to move the needle, flexible enough to match your runway.

Technical strategy & roadmap ownership
Architecture reviews & decision records
Engineering hiring & onboarding support
DORA-informed delivery metrics & retros
Board & investor technical comms
Code review & team coaching

Discuss a fractional role →

Between these? Custom scopes welcome.

Most engagements don't fit a neat box. If you have a budget in mind and a problem to solve, we’ll shape the scope to fit, from smaller builds (from £8,000) to larger multi-phase deliveries. One call, one honest estimate, no pressure.

Discuss a custom scope →

Get in Touch

Let's build
something great

Every project is unique. Tell us what you're working on and we'll respond with ideas, a rough scope, and honest advice. All engagements are priced individually.

Not sure what you need?

Book a free 30-minute advisory call. We'll talk through what you're trying to build, and I'll give you an honest view on scope, cost, and whether we're the right fit. No sales pitch.

📅 Book a 30-min Call

Prefer email?

✉️ Email Us Directly

Emailhello@walsh.london

Webwalsh.london

Reg.Walsh London Ltd · No. 16949730

Thank you, we'll be in touch shortly.

We build softwarethat actually ships

Receipts fromrecent engagements