唐津くんち曳山ナビ is a navigation app available for iPhone and iPad that provides users with a simple way to track the location of the traditional Japanese festival called "唐津くんち" (Karatsu Kunchi). This festival, which takes place over three days in Karatsu City, Saga Prefecture, attracts over 500,000 visitors each year. The app utilizes the festival schedule to estimate the position of the festival floats, known as "曳山" (Yamayama), at different times.

With the help of GPS, users can also determine their own location and find the distance between their position and the estimated location of the festival floats, as well as the distance to the points where the floats pass by.

In addition to the festival navigation features, the app now includes information on nearby convenience stores such as Seven Eleven, Lawson, and Family Mart, as well as souvenir shops like Furusato Kaikan Alvino. It also provides information on dining options, restrooms, parking areas, tourist attractions, hotels, and ryokans.

For those interested in the history of the festival floats, the app offers historical information about each of the 14 floats. It also includes links to abstracts about the festival and floats at Karatsu Shrine.

The app now features a demo function that allows users to simulate the festival procession and receive notifications and updates from the festival headquarters. If the festival floats are equipped with GPS and the service is active, users can track the real-time position of the floats using the map view.

With 唐津くんち曳山ナビ, users can familiarize themselves with the festival route in advance to prepare for the main event on November 2nd, 3rd, and 4th. The app has recently been recognized as a UNESCO World Cultural Heritage.

Furthermore, the app has implemented references to the local film "Hanakago" which features Karatsu Kunchi as part of its historical background and has been released nationwide.