A business owner herself ... There are several free invoice maker apps that you can use for your billing. The best free invoice and billing apps include Zoho Invoice, Invoicely and Square.

Some time tracking solutions also help you calculate project billing and invoice clients directly from the app. The best employee tracking app for your business will depend on your goals.

But of course, not every business likes emojis alongside their invoices, and that's where apps like PayPal — which has a slightly more sophisticated invoicing set-up — come in. Factors like ...

Additionally, dedicated invoice apps often offer integrations with other tools, such as accounting or project management software, making it easier to manage all aspects of your business.