37signals Developerland is where we publish our APIs and other bits of interest to developers. Our APIs are implemented as vanilla XML over HTTP. We currently publish the Highrise API, the Basecamp API, the Backpack API, and the Backpack Calendar API. You can also check out the Unofficial Campfire API if you'd like to integrate with Campfire.
Basecamp is our popular project management and collaboration tool. Over 1,000,000 people in over 75 countries have accounts. A wide variety of third-party products already integrate with Basecamp using the Basecamp API.
Highrise is our contact/task management and simple CRM tool. Over 600,000 contacts are being managed with Highrise. Highrise is our newest product.
Backpack is our simple "get yourself organized" tool. Over 200,000 users have added over 8,000,000 to-dos and 1,200,000 notes to their Backpack accounts. In addition to the standard Backpack API, we offer a specialized API for the Backpack Calendar.
Campfire is our real-time persistent chat tool for groups and businesses. Over 15,000,000 messages have been sent back and forth using Campfire. Note: This API is offered by a third party and not officially supported by 37signals.
