Backend Development
Resilient services and APIs designed to scale quietly in the background, so products stay fast and dependable.
- Scalable APIs
- Cloud architecture
- Secure integrations
- High-performance services
- Reliable infrastructure
Callum Ilett /London & Hertfordshire, UK
AI, Built for Production
I design and build production grade LLM applications, combining RAG pipelines, agentic workflows and tool integrations with reliable infrastructure and polished user interfaces.
Skills & services
What I Build.
From ambitious ideas to polished digital products, I create reliable technology that delivers exceptional experiences.
Mobile Development
Cross-platform apps that feel native in the hand — smooth, responsive and considered down to the last gesture.
- Cross-platform applications
- React Native
- iOS and Android
- Native-feeling interactions
- Performance and usability
Website Development
Modern web applications with clean architecture, accessible interfaces and interactions that delight.
- Responsive web applications
- Modern frontend architecture
- Accessible interfaces
- Performance optimisation
- Interactive experiences
Technology stack
The Technology Behind the Experience.
A deliberately chosen toolkit, each piece earning its place in an ecosystem built for speed, safety and scale.
React
Component-driven interfaces with predictable state, server rendering and fine-grained performance tuning
Expo
Managed native builds, over-the-air updates and a fast mobile developer loop, one codebase, two native platforms
TypeScript
End-to-end type safety that turns runtime surprises into compile-time conversations
PostgreSQL
Relational data modelling with strong consistency and expressive queries
.NET
High-throughput APIs and background services in C#, built on minimal APIs and clean architecture
Microsoft Azure
Cloud-native hosting, identity, messaging and observability with infrastructure as code
Featured projects
Selected Work.
A collection of digital products where thoughtful engineering meets refined design.
Health & Wellness · Mobile App
Aeson
2026
A React Native app that connects people to massage and recovery devices in gyms, with prepaid credit spent by the minute.
- React Native
- TypeScript
- Tailwind CSS
- Jest
- +1 more
Employee Platform · Mobile App
Three Engage
2023
An employee platform that brings a social feed, company news, events, recognition and daily tools into one mobile app.
- React Native
- TypeScript
Internal Communications · Web AppThree Intranet
2022
A custom-built intranet where Three UK employees create, share and discuss company news, events and updates.
- React
- TypeScript
Employee Assessment · Web AppA web platform where store managers build custom observation forms, with branching logic, reports and spreadsheet export for administrators.
- React
- TypeScript
Testimonials
Words From People I've Worked With.
“I had the pleasure of working alongside Callum over the last 2 years. Callum consistently delivered on what was tasked and was able to effectively communicate to shareholders across different disciplines leading to better outcomes. He would be an asset to any team.”
Josh BrowningWeb Developer · .NET“Callum has worked for UXC for the past three years, straight out of university, and I have watched him grow to become an extremely competent full-stack developer. I’m very proud to be able to make this recommendation, Callum is a true asset to any development team.”
Matthew GoddardUX Consultancy Ltd(Owner)“Callum has a wealth of knowledge in multiple development languages and is a pleasure to work with. Callum has great visibility communication which is critical for successful remote working. He was pivotal in sizing client work and understanding development best practices and technologies to ensure we delivered projects that were clean, and on time.”
Marcus WoodbridgeSenior Digital Product OwnerExperience
My Career, on One Page.
Where I've worked, what I've shipped and how I can help you, ready to download and share.
Curriculum vitae
"Great software is never really finished."
It's thoughtfully engineered, carefully designed, and continuously improved.
Download CVPDF
Social
Let's Connect Beyond the Code.
- GitHub@Callum-IlettOpen-source work, experiments and side projects.(opens in a new tab)
- LinkedInin/callum-ilettCareer history and professional updates.(opens in a new tab)
- Instagram@callum.ilett99Personal life and interests.(opens in a new tab)
- Facebookcallum.ilett.1Personal life and interests.(opens in a new tab)
Start a project
Have Something Brilliant in Mind?
Whether you're launching a new product, improving an existing platform or exploring an ambitious idea, I'd love to hear about it.
- Idea
- Plan
- Design
- Develop
- Launch