BOULDER - Now available: A tour guide small enough to fit in your pocket and smart enough to know what you want to learn before you look it up, according to Tagwhat Inc., a Boulder-based mobile app startup.

Tagwhat launched its app Monday. The app, which runs on iOS and Android, uses the GPS capabilities of a device to determine where users are. The app then brings up web-based content to tell users more about their location.

"It's basically tethering web content to a physical location," Tagwhat founder and chief executive Dave Elchoness said.

Tagwhat can be thought of as a mobile tour guide, one that is always updating itself with the latest information from the web, Elchoness said. The material Tagwhat retrieves includes text, video and pictures. Businesses and organizations that use the app can link Facebook and Twitter pages to their channels.

Users can call up information, but the app also delivers it. Users tell the app what they're interested in, such as historic landmarks or restaurants, and Tagwhat brings up information for them as they approach a relevant site.

Using Tagwhat in Boulder, for example, will bring up Wikipedia articles about nearby landmarks, a University of Colorado-Boulder campus tour and the channels of local restaurants.

Monday marked the official launch of Tagwhat. Versions of Tagwhat have been available for iOS and Android, but those early versions lacked major features and the polish of the current version.

"We're really seeing the product take shape, and I think now we have a really nice collection of features," Elchoness said.

Among the features are tools users can use to create their own links between a location and web pages, and a dashboard publishers can use to upload digital content they have created.

Tagwhat's app was three years in the works, Elchoness said. During that time, the six-employee company relied on investment from the founders and their friends and families.

Tagwhat wanted to have a well-working product before it began courting outside investors, Elchoness said. With the recent upgrades to the app completed, the company now is ready to approach investors, he said.

Tagwhat has been generating revenue from publishers such as tourism bureaus, colleges and heritage societies that are using the service to create branded channels. An example is the Colorado Department of Transportation, which has created a tour guide of scenic byways. Users load up the Tagwhat app, go to the CDOT channel, and the app retrieves information about nearby landmarks.

Tagwhat is operating on a "freemium" business model, which means it will be free to download and use for consumers. Businesses and organizations can create branded channels for a fee. At the moment, many of the links are to Wikipedia entries, but some Boulder-based businesses have created channels with written histories, pictures and video.

Tagwhat also plans to generate revenue from affiliate deals with daily-deal sites such as LivingSocial, Elchoness said.