We started this year with the aim to integrate with as many useful third-party services as we could. We wanted to enhance the power of Teamwork Projects and allow people to continue to use the services that make their job easier.
Teamwork Projects - Integrations
One of the joys of cloud-based computing is that there are now more options available to link multiple services together. All that’s required is a good API. We wanted to put one post together that would act as a good reference point for all existing and future Teamworkers to go to if they needed to quickly see what was available to integrate with and, more importantly, how to hook Teamwork Projects up with these apps and services.
A full list of our integrations to date: 
Freshbooks: A fast and simple invoicing and time tracking service that help you manage your business and get paid.  Read more here.
Harvest: Simple time tracking, fast online invoicing, and powerful reporting software. Simplify employee timesheets and billing. Read more here.

BlinkSale:  Is perfect for anyone who needs to invoice clients for services or products sold.

Dropbox: Is a free service that lets you bring your photos, docs, and videos anywhere and share them easily. Read more here.
Quickbooks Online: Accounting software creates invoices, pays bills, and tracks expenses. Manage business accounting online quickly and easily. Read more here.
Xero: Online accounting software for business. Web-based system for invoicing/billing, accounts payable, bank reconciliation and bookkeeping. Read more here.

Box: Simplifies online file storage, replaces FTP and connects teams in online workspaces. Read more here.
Google docs, now known as Google Drive: Create and share your work online and access your documents from anywhere. Manage documents, spreadsheets, presentations, surveys, and more. Read more here.