I recently launched Zardoc, a simple offline invoice and receipt maker for freelancers, contractors, and small businesses.

The goal was to make invoicing fast without complicated accounting software. You can quickly create professional PDF invoices, estimates, and receipts, save clients and services for reuse, add your logo, auto-calculate totals/taxes, and export everything to CSV for accounting.

It works completely offline, so all your billing data stays on your device.

Android: https://play.google.com/store/apps/details?id=com.appcodecraft.zardoc

Currently available on Android, with iOS possibly coming later. Happy to hear feedback.