A Kiwi developer has created an app to help with booking Great Walks.

Last May, 20,000 bunks on the Milford Track were snapped up in minutes, but this app tracks cancellations, telling people who missed out if a bed becomes available.

App developer James Morgan says more than 700 people have signed up so far.

"And I've had a lot of feedback of people saying 'thank you' and 'this is amazing', which is always good to hear as well."