Hello, I'm Sergio Díaz
a Mobile Developer
Flutter and iOS apps
for companies that can't afford bugs
About Me
Freelance Mobile Developer specialised in Flutter and native iOS (Swift, SwiftUI). I've built DigiAcción's mobile app and my own products like LiftIQ. I work end-to-end: from architecture to App Store and Google Play deployment. With 6+ years of prior full-stack experience (.NET, React, AWS), I bring technical context most mobile devs lack.
Experience
Freelance Mobile Developer
Self-employed
Software Developer
Ohtic
Software Developer
Bdr Informática
Java Developer
Logaritme
Software Engineer Intern
Avanade
Main Stack
AI & Agentic Dev
Claude Code Claude Skills 
AI Agents Mobile
Flutter 
Dart 
Swift SwiftUI UIKit 
Xcode Tools & DevOps
Docker 
Git 
GitHub Actions 
Linux VPS 
AWS Backend
.NET 8 
MySQL Entity Framework Frontend
React 
TypeScript 
Next.js 
Tailwind CSS Featured Case Studies
Project Portfolio
Boxpush — Push Box Puzzle
Sokoban-style puzzle game with 500 generated, verified levels: every one comes with its optimal solution
DigiAcción — Mobile App
Cross-platform Flutter app developed for DigiAcción, fully integrated with their backend
Southpaw — Boxing Round Timer
Round timer for boxing, MMA, Muay Thai and HIIT in SwiftUI: niche picked from ASO data, TDD engine, and an App Store listing built entirely through the API
LiftIQ — Barbell Tracker
iOS app to track barbell training: sets, RPE, progression and personal records
Trusted Companies
Companies I have worked with
Background across different sectors, with a current focus on mobile.
Mobile Clients
Other clients
Prior work in .NET, React, and other technologies. My focus today is 100% mobile.
How can I help you?
Services Offered
High-quality native and cross-platform mobile application development
Cross-Platform Mobile Development
Native apps for iOS and Android with Flutter. Single codebase, native performance, and perfect UX on both platforms.
- Flutter (iOS & Android)
- Clean & scalable architecture
- Pixel-perfect UI/UX
- REST/GraphQL API integration
Native iOS Development
Native iOS applications with Swift and SwiftUI. Maximum performance and leveraging the latest Apple features.
- Swift & SwiftUI
- Apple ecosystem integration
- Push notifications & deep linking
- Core Data & iCloud sync
Deployment & Maintenance
Automated CI/CD for App Store and Google Play. Frictionless updates and continuous monitoring.
- CI/CD (Fastlane, GitHub Actions)
- App Store & Google Play deployment
- Crash reporting (Firebase, Sentry)
- Analytics & performance monitoring
Custom quotes based on scope
How I work
Transparent process
From idea to production-grade app, with clear milestones at every stage.
Discovery
1 week
- Kickoff call to understand context and goals
- Scope and MVP definition
- Detailed proposal with milestones and timelines
Design & architecture
1-2 weeks
- Wireframes reviewed with you
- Stack and architecture decisions
- Milestone-based delivery roadmap
Build
4-8 weeks
- Iterative development, one feature at a time
- Weekly demos with your team
- Tests and CI/CD from day one
Ship & support
1 week + 30 days
- App Store and Google Play deployment
- Technical documentation and handoff
- 30 days post-launch support
Testimonials
What Clients Say
Testimonials from companies I've worked with
"Sergio led the development of our platform from scratch. His ability to translate business requirements into scalable technical solutions was fundamental to our success. The system processes thousands of transactions daily without issues."
Aitor Ruiz
CEO @ GetaLink (platform Sergio leads technically)
GetaLink
"Sergio developed our mobile app with Flutter flawlessly. His attention to detail in UI/UX and seamless backend integration resulted in an app our users love. Fast, professional, and highly communicative."
Jesus Almir
CEO DigiAcción
DigiAcción
Want to be the next satisfied client?
Let's work togetherFAQ
Frequently asked questions
What everyone asks before starting a project with me.
Do you work under NDAs?
How do you bill?
Is there a post-launch guarantee?
Do you work with in-house teams?
Let's Work Together
Have a project in mind? Schedule a 30-minute call with me.