TimeBridge is a San Francisco-based startup focused on making it easy to schedule meetings and appointments. In a relatively crowded market, the product has managed to show impressive growth over recent months, this week surpassing the 200,000 user mark, with over 12,000 businesses using the service.

TimeBridge recently announced its product’s ability to sync with Apple iCal as well as with established calendar apps such as Google and Outlook. There has been speculation about the possibility that such rapid growth has been partly achieved through questionable means, specifically by one’s contacts being mass emailed when Google Calendar is synced with TimeBridge’s calendar. We tried to replicate this scenario, getting to the point at which TimeBridge supposedly sends out these invitations; although it is possible, you are given absolutely every opportunity to ensure that invitations are not sent out.

TimeBridge’s stand-out feature is the simplicity with which it gives recipients alternative times and dates for each appointment. The appointment organizer sends out invitations with five optional times, and attendees are requested to select “Yes,” “No,” or “Best.” If a particular time appears to be the “Best” for all attendees, TimeBridge will automatically set it as the time of the appointment. Otherwise, TimeBridge notifies the organizer of the alternatives and awaits confirmation.

We’ll go into TimeBridge and other scheduling applications, such as Doodle and Tungle, in more detail in an upcoming post.