Cross-Platform Invoicing & Customer Management App

I am looking for a developer to build a simple, reliable business application that works on both MacBook (macOS) and Android smartphones. The purpose of the app is to manage products, customers, and invoices while allowing invoices to be created and sent while on the move.


Core Features Required

Product Management

Ability to add, edit, and delete products

Store product name, quantity, and standard pricing

View a list of all products

Ability to quickly select products when creating invoices

Customer Account Management

Create and manage customer accounts

Store contact details and payment terms

Ability to apply customer-specific discounts on particular products

Standard pricing should still apply for other customers

Invoice Creation & Management

Create invoices quickly while on mobile

Automatically generate unique invoice numbers

Add products to invoices from the product list

View and manage all invoices

Send invoices directly from the app via email

Email Automation

When an invoice is created, it should automatically be emailed to:

The customer

My accounts department email

Automatic overdue reminder emails sent to customers when invoices become 1 day overdue

Payment Tracking

Ability to mark invoices as paid

Additional Requirements

Clean and simple interface

Reliable data storage (cloud preferred so it syncs between devices)

Secure login system

Ability to export invoices or reports if needed

Documentation or brief handover explaining how to maintain or modify the system


PDF invoice generation

Dashboard showing outstanding invoices

Basic reporting (paid vs unpaid invoices)



What I’m Looking For

An experienced developer with examples of similar work

Advice on the best technical approach

A scalable solution that can be expanded later if needed

Please Include in Your Proposal

Suggested technology stack

Estimated cost

Estimated timeline

Examples of similar apps or systems you have built