When combined with some of the additional features covered below, we think Square Invoice is one of the best apps for business owners who want to centralize their payment and invoicing needs.

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.

Messaging apps like Slack are essential for communicating with ... data aggregation mechanism using simple event-action ...

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.