Multi-Platform Billing App Development

I'm looking for a skilled developer/team to create a comprehensive billing app similar to Vyapar. The app must support iOS, Android, and Windows platforms.

Key Features:
- Invoice Generation
- Expense Tracking
- Inventory Management
- Multi-Field Vendor Support

The app should also allow for moderate customization of invoice templates, including custom fields and branding.

Ideal Skills:
- Cross-platform app development
- Experience with billing/inventory management apps
- UI/UX design for custom invoice templates

Please provide examples of similar projects you've done in your bid.

https://vyaparapp.in/blog/vyapar-app-complete-feature-list-all-about-your-favorite-billing-software/