Developer builds macOS banking app with Claude Code in 6 weeks

What was built

A developer built simplebanking, a free, open-source macOS menu bar application for German banking. The developer describes themselves as "a product & strategy person, not an engineer" and created the app almost entirely with Claude Code in about 6 weeks. The app currently has approximately 1,000 daily active users.

App features

• Lives in the Mac menu bar and shows live balance across multiple German bank accounts
• Read-only functionality with no payment capabilities
• Instant transaction search
• Automatic subscription detection with cancel links
• Financial health score
• MoneyMood heatmap for spending patterns
• All data stays locally on the Mac: no server, no tracking, no ads
• Built on Open Banking via YAXI

Development approach with Claude Code

The developer shared specific techniques that worked well when building with Claude Code:

• Treat Claude like a colleague to learn about architecture
• Use Plan mode to let Claude think in steps before touching any code
• Use branches extensively - described as "non-negotiable"
• Provide pixel-perfect descriptions of what should go where on screen
• Tell Claude to change exactly one thing at a time and explicitly not touch the rest to avoid merge conflicts
• Structure prompts with constraints and clear definitions of "done"
• Use Gstack to keep everything organized across prompts, flows, and overall architecture

Project outcomes

After development, experienced engineers conducted a full code review to catch issues and, by their own admission, to "steal a few ideas for their own projects." The developer noted unexpected criticism in some circles for using AI, despite the app's success and user satisfaction.

The app is available at www.simplebanking.de and the source code is on GitHub.