Freelancer Time & Earnings App

I’m looking to turn a simple idea into a working tool: an app that lets me hit “start”, get to work, hit “stop”, and instantly see how much I’ve just made. The core job is to build a clean, reliable tracker focused on two things—time logged through a start/stop timer and automatic earnings calculation based on a preset hourly rate.

Here’s what matters most to me:

• Start/Stop Timer – one tap to begin, one tap to end, with totals stored in the background.
• Automatic Earnings – each second tracked should be multiplied by an hourly rate I set, then rolled into a running balance I can view at a glance.

I don’t need manual time entry or elaborate activity-tracking right now, but I’d like the architecture to be flexible enough that we could add those later without a full rewrite. A simple summary screen, a daily/weekly/monthly breakdown, and the option to export or copy the figures into a spreadsheet would round things off nicely.

Deliver the compiled app, all source code, and a brief read-me that shows how to build and deploy it. If you can suggest a lightweight cross-platform stack that keeps future features open, even better.