Lumen
A personal finance companion that explains money in plain language, on iOS and Android.
This is a concept exploration created by Senume. It does not describe a client engagement, and no results are claimed as real.
The problem
Most finance apps present numbers without meaning. People open them, feel vaguely worse, and close them again. The brief was an app that makes everyday money decisions feel lighter.
- Role
- Design and native engineering
- Timeline
- 12 weeks (concept)
- Services
- Experience Design, Mobile Engineering, Design System
- Platforms
- iOS, Android
- Technology
Constraints
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Strict privacy expectations — sensitive data should stay on device wherever possible.
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One shared business logic layer, two genuinely native interfaces.
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Accessible typography and contrast for long-form explanations.
Solution
The product began with a single sentence test: could every screen be summarised in one plain sentence? Screens that failed were redesigned or removed.
Business logic is shared through Kotlin Multiplatform, while the interfaces are written natively in SwiftUI and Jetpack Compose so each feels at home on its platform. Transaction categorisation runs on device with a compact model, keeping personal data where it belongs.
How it flows
- Accounts
- On-device model
- Insights
- Weekly story
Results
Intended outcomes — concept project
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Plain-language insights
Weekly summaries written like a thoughtful friend, not a bank statement.
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Native on both platforms
Shared logic, platform-true interaction on iOS and Android.
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Privacy by design
Categorisation runs on device; the server never sees raw transactions.
What we learned
- Tone of voice is an interface element and deserves the same iteration as layout.
- Shared logic pays off most when the UI layer is allowed to stay fully native.