FreshBooks is an online invoicing service with a few goals in mind: easy & fast record keeping, simple billing, and safe data. It’s no wonder they have over 3.5 million clients! With this kind of client base, FreshBooks opened up their API to 3rd party developers to create their Add-on Store, where developers can create and promote applications that integrate directly with FreshBooks clients’ accounts.
The FreshBooks API site gives a brief overview of the service before it goes into more detail about authentication, application-specific billing, webhooks, and their various endpoints. They also provide links to API libraries published by other developers in Ruby, Python, PHP, Perl, and others, making connecting to the API a snap. The Sample Code page also helps quite a bit, with examples for authentication, plugins, third-party apps, and their own internal integration code as well. FreshBooks uses OAuth for authentication, similar to other modern API platforms, and has full documentation and examples to get you set up.
Examples of applications that have been built with the FreshBooks API can be seen on their add-on community page, and include project management, customer management, accounting, expense, time tracking, lead generation, marketing, payment gateway, productivity, and eCommerce software packages. FreshBooks also maintains a developer blog, tips page, and google group for fielding any API / development questions.
Corey from FreshBooks is one of the founding members of HackDays, and FreshBooks’ API has been at hackdays since the beginning. Their API will be a sponsor at HackREGINA, HackVan, and HackTO this year.