Hot calendar app Tempo crushed by demand

Buzzy calendar and scheduling app Tempo, which made a splashy launch yesterday, is recovering after being overrun by new users.

"We are excited but overwhelmed by the demand," Raj Singh, the founder and CEO of Tempo, wrote in a blog post today.

Shortly after the app went live, Tempo was forced to close down new signups, incensing would-be users and leading to a bevy of negative reviews in the App Store.

Singh now says the company is opening up the service to users in batches, and changing how it lets users access certain features. That includes once again letting people register (something that earlier threw up error messages), as well as connect their calendars, address book, and e-mail account to the software.

The only thing the service won't do as quickly is cull through e-mail to find relevant messages, a key feature that Singh says is experiencing delays.

Tempo is a spinoff from SRI International, the same place where Apple's Siri was conceived. The software is designed to improve the way people accomplish common business activities on their phones, from conference calls to getting driving directions to meetings.

The demand issues are not the first for a productivity app on Apple's platform in recent days. Mailbox, an e-mail application for Gmail, quickly racked up a more than 700,000 user long wait list to get access to the app, which relies on servers to add lists, reminders, and notifications beyond what Google already offers. That service has been experiencing sync issues, with some users reporting an inability to access their inbox.