A free program for Android, by Zybra Pvt Ltd.

GST Billing Invoicing Accounting & Inventory App is a GST-compliant Billing & Accounting App that lets a business owner keep complete control of his business accounting, stock/inventory, Invoicing, Billing, Estimates, Expenses, GST tax & more. It keeps you in full control of the business in a very simple & easy way.

The app supports multiple businesses such as retail, wholesale, etc. 

GST Billing Invoicing Accounting & Inventory App is an ideal app for any business owner who wants to grow his or her business. The app allows the user to manage all the accounting activities such as managing billing, account books, ledgers, payments, inventory/stock, etc from anywhere & at any time.

The app allows the user to create estimates, bills, and invoices.