| API | Description | Category | |
|---|---|---|---|
| 43 Places | Social travel goals | Community | 2008-07-02 |
| 43Things | Social goal setting | Other | 2005-10-30 |
| GroupMe | Social bookmarking | Bookmarks | 2007-12-25 |
| Tagalag | Email tagging | Tagging | 2005-10-05 |
| tagthe.net | Tag recommendation service | Tagging | 2006-07-03 |
| Tagyu | Tag recommendation service | Tagging | 2005-10-29 |
| Topicalizer | Document analysis service | Other | 2006-03-23 |