Available for new projects

Your app,
from idea to App Store.

End-to-end mobile development for SaaS companies and startups: mockups, native iOS, web, APIs and backend, security, testing and store release. Android through a trusted partner. Thought by humans, accelerated by AI, reviewed by a senior engineer.

Start your project See how it works
Cheese@home iOS app — cheese-making recipes Cheese@home
Andaman7 iOS app — patient health record Andaman7
Circuit Court iOS app — local shops Circuit Court
SaaS
multi-tenant & white-label platforms
12 yrs
of apps running in production
9
stages, mockup to maintenance
2
native platforms, Android with a partner
Services

Everything your product needs.
Nothing it doesn't.

A senior engineer for the whole mobile stack, teamed with a trusted Android partner when you need both platforms. No agency overhead, no juggling a crowd of freelancers.

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Mobile apps for SaaS

Native companion apps for your platform: accounts and roles, multi-tenant data, subscriptions and in-app purchases, offline sync, push notifications, and white-label variants for your customers, all from a single codebase.

Multi-tenantWhite-labelSubscriptions Offline syncPushSSO
Andaman7 health record summary on iPhone
Circuit Court map of local merchants
Cheese@home recipe on iPhone

Native iOS

Fast, accessible, polished apps for iPhone and iPad, built with Apple's latest frameworks and design language.

SwiftSwiftUIUIKitLiquid GlassWidgetKitLive ActivitiesStoreKit 2

Web services & backend

Documented REST APIs, authentication, database, file storage, push and third-party integrations. Sized for where the product is today, ready to scale.

REST / OpenAPIOAuth 2 / OIDCFirebaseJava Spring

Websites & back-office

Marketing sites and landing pages that sell the app, plus admin dashboards to manage users, content and customers. Fast, multilingual, SEO-ready.

ReactTypeScriptViteFirebase Hosting

Sensitive & health data

A specialty built over a decade of healthcare SaaS: encrypted sync, consent, GDPR, audit trails, and interoperability with hospital systems through FHIR and HL7 when needed.

RGPD / GDPREncryptionFHIR / HL7Clinical trials

Existing apps & tech lead

Taking over or scaling an existing app: legacy Objective-C/Swift modernization, CI/CD and release processes, AI tooling for the team, and technical leadership.

MVVMClean ArchitectureCI/CDCode review
+
iOS and Android

Two platforms. One team you can trust.

Need Android too? A trusted Android engineer with the same background and standards joins the project. You work directly with both of us, on one shared architecture, one backend and coordinated releases.

Meet Martin Marot, the Android partner
The complete process

From first sketch
to App Store, and beyond.

Every stage of a professional mobile project, covered and documented.

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01

Discovery & scoping

Goals, users and business model turned into a prioritized MVP scope and a clear quote.

WorkshopsUser journeysRoadmapQuote
02

UX & UI design

Wireframes, high-fidelity mockups and a clickable prototype, following Apple and Material guidelines.

MockupsDesign systemPrototypeAccessibility
03

Architecture

Foundations that won't need a rewrite: data model, API contract, hosting and a testable app structure.

Data modelOpenAPIMVVMClean Architecture
04

App development

Native iOS in SwiftUI, Android in Kotlin with the partner, with regular test builds along the way.

Offline modePushIn-app purchasesLocalization
05

Web services & backend

Documented APIs, authentication, database, storage and the integrations your product relies on.

REST APIsOAuth 2 / SSOBack-officeIntegrations
06

Security & privacy

Built in from day one: encryption in transit and at rest, secure sessions, GDPR by design.

EncryptionKeychainOWASP MASVSGDPR
07

Testing & quality

Automated tests on critical paths, CI on every change, beta testing and crash monitoring.

Unit & UI testsCI/CDTestFlightMonitoring
08

Launch & delivery

Store submission through review, localized store listings, marketing site and a clean handover.

App StorePlay StoreWebsiteDocumentation
09

Maintenance & evolution

OS updates, dependency upgrades, fixes and new features driven by real usage.

OS updatesSecurity patchesNew features
Selected work

Proven in production.
Building what's next.

A health SaaS platform in production for twelve years, and two new products currently being built end to end with the AI workflow.

Andaman7 app icon Health SaaS · 2014 – 2026

Andaman7

A health-data SaaS platform: patients gather their medical records in one app, share them securely with doctors and family, and take part in international clinical trials. The platform serves partners through white-label apps built from the same codebase.

  • White-label apps for partners from a single codebase
  • End-to-end secure synchronization of medical data
  • Interoperability with hospitals and research partners
  • Gradual Objective-C to modular Swift migration, no rewrite
SwiftUIKitCore DataJava SpringFHIR
andaman7.com
12
years in production
iOS
lead, then Tech Lead
iPhone+iPad
universal app
Andaman7 medical timeline
Andaman7 medication list
Andaman7 medical documents
Cheese@home app icon In progress · Consumer app

Cheese@home

A companion for making real cheese at home: 40+ guided recipes with variants, smart timers that survive closing the app, and a cellar that looks after cheeses while they age, synced through iCloud. Being built end to end with the AI workflow, from mockups to marketing site.

  • Lock Screen countdown, home-screen widget and real alarms (AlarmKit)
  • iCloud sync (CloudKit), one-time premium unlock (StoreKit 2)
  • App and website in 7 languages, iPhone Duo ready
SwiftUILiquid GlassClean ArchitectureSwift Testing
cheeseathome.hannay.be
Cheese@home cheese-making timer
Cheese@home cheese cellar tracking
Circuit Court app icon In progress · B2G SaaS

Circuit Court

A civic loyalty SaaS designed to be funded by municipalities. Residents complete local quests, earn points and spend them at independent shops. Product model designed for a bounded budget and no e-money regulation; iOS app and website in development.

  • Product strategy and B2G business model
  • Map-based discovery, quests and QR validation
  • Rules configurable per municipality, multi-tenant by design
SwiftUIMapKitSaaSWeb
circuit-court.web.app
Circuit Court merchant page
Circuit Court loyalty rewards
Why it costs less

AI-accelerated.
Senior-reviewed.

AI now handles the repetitive part of software work: scaffolding, boilerplate, tests, translations, store assets, documentation. Architecture, security, UX and the final review stay in expert hands.

Faster

An MVP in weeks, not quarters. Work that used to fill whole sprints now takes hours.

Leaner

Fewer billable hours spent typing, more spent deciding. The budget goes to expertise, not boilerplate.

Solid

Every change reviewed, tested and documented, so the codebase stays maintainable by any team, human or AI.

What AI accelerates

  • Scaffolding, models, networking boilerplate
  • Unit tests and edge-case coverage
  • Translations, store listings, screenshots
  • Docs, migration scripts, refactors

What stays in expert hands

  • Product decisions and architecture
  • Security, privacy and sensitive data
  • UX details and the "feels right" polish
  • Review and sign-off before anything ships
Working together

Pick the shape
that fits your stage.

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For founders & new products

MVP Launch

  • Stages 1 to 8: from mockups to store release
  • Fixed scope and price, agreed upfront
  • App, backend and marketing site
  • Test builds to try the app as it grows
Plan an MVP
Recommended For growing SaaS products

Product Partner

  • Monthly retainer with dedicated capacity
  • New features, maintenance and OS upgrades
  • Roadmap input and release management
  • Android covered with the partner
Let's talk
For teams with an existing app

Existing app

  • New features on an existing codebase
  • Legacy rescue and modernization
  • AI tooling brought into the team's workflow
  • Part-time Tech Lead or mentoring
Discuss your app
Sébastien Hannay, freelance iOS developer
Behind the work

Sébastien Hannay

Senior iOS engineer & tech lead · Liège, Belgium · Remote across Europe

Twelve years building and leading a health SaaS platform used in clinical trials, now available to help SaaS companies, startups and health players ship mobile products with healthcare-grade rigor and modern AI speed.

  • 2026 · NOW
    Freelance mobile product engineer
    Cheese@home, Circuit Court, and your project?
  • 2019 – 2026
    Tech Lead · Andaman7
    Mobile & backend roadmap, code review, release processes
  • 2014 – 2026
    Senior iOS Engineer · Andaman7
    Flagship iOS app, secure medical data sync, white-label
Full résumé French · English

Questions, answered.

Yes, because AI works inside strict guardrails: a clear layered architecture, written project rules, automated tests and a human review of every change. The result is a codebase any senior developer can pick up, and that AI tools can keep extending safely.

From the architecture stage: encryption in transit and at rest, secure authentication, role-based access, data minimization, consent and deletion flows, checked against OWASP mobile guidelines. Real personal or health data never goes into AI tools; they work on code and synthetic data only.

Yes. Native Android is built by a trusted partner with a similar background. Both apps share the architecture and the backend, and releases are planned together so they evolve in step and stay consistent.

You do, from day one. Repository, App Store and Play Store accounts, cloud projects and intellectual property are all in your name. No lock-in.

Absolutely. Large Objective-C/Swift codebases can be taken over and modernized step by step, without stopping delivery.

Let's build
your app.

Describe your project in a few lines. You'll get a reply within one business day with first thoughts and next steps. No commitment.

What do you need?
Where are you at?

Opens your email app with the brief pre-filled.

Or get in touch directly sebastien@hannay.be linkedin.com/in/sebastienhannay github.com/sebastienhannay