Acoustic Tanpura is a free iPhone app developed by Vijayalakshmi Ranganathan, designed for musicians and vocalists to tune to specific pitches or Shruti. This app features a virtual acoustic tanpura with manually tuned pitches, ideal for practice sessions, performances, yoga, and more. Users can select from English, Hindustani, or Carnatic pitch labels and utilize the Sa-Pa-Sa chorus helper for vocal practice. The app offers three speed options for pitch playback, volume control, and the ability to set the first string as Madhyamam. Additionally, users can play the app in the background with convenient pause control on the status panel, featuring original sounds.