The best alternatives to The Application ToolKit are Stripe, AND.CO, and InvoiceNeko. If these 3 options don't work for you, we've listed a few more alternatives below.
Stripe is a technology company that builds economic infrastructure for the internet. Businesses of every size—from new startups to public companies—use our software to accept payments and manage their businesse...
From proposal to payment, AND.CO takes the headache out of freelancing, so you can get back to the work that drives you. Invoicing, Time Tracking, Payments, and More For Freelancers and Independent Contractors
Invoice Neko is a self-hosted open sourced invoicing system built on a modern backend with a focus on delivering a good user experience throughout the application
Our team created this app to make invoicing simple and accessible. There are no complicated forms. No in-app purchases. Send beautiful invoices quickly and get back to building your business.