Shopify has its own online invoice generator to make it extremely simple for merchants to process billing and collect money
All you need to do is fill in the required information in the invoice generator to create the invoice. You can then email it directly to your clients. It also gives you the option to save or print the invoice.
The Shopify invoice generator is also completely free of cost! It’s also available for everyone and not just limited to merchants using Shopify
Here’s a link to the Shopify invoice generator: https://www.shopify.in/pos/invoice-generator