The Organ Web App is developed as part of the Organ Project undertaken by the Union Chapel, a 19 century Gothic style church which serves as a popular live entertainment venue in the Islington area of London, England. The venue is famous for its Henry Willis pipe organ built in 1877 and successively restored in 1946 and 2013. The aim of The Organ Project is to make the pipe organ more accessible to the local community and beyond. The project not only honours the legacy of this instrument by keeping up a recital diary, but also encourages performers to play it in different styles. The versatility of the organ is also reflected in the education strand for adults and children. However, audiences, including people who have never been to the Union Chapel have no access to the organ, which is hidden away behind screens at the chapel. Therefore the Organ Project would like to reach out beyond the live audiences by creating an app that provides users with information about the Henry Willis organ and enable them to even play it and experience its sounds. For this reason, the chapel commissioned the development of The Organ Web App. With the help of web technologies, The Organ Web App achieved both the artistic and pedagogical goals of The Organ Project.  It presents different aspects of the Henry Willis pipe organ through a virtual tour, including its history, pipes, console and hydraulics. The Web Audio API provides a powerful mechanism to retrieve, playback and manipulate audio content inside a web app. Sample-based synthesis was used to deliver a faithful organ playing experience as best as possible on a computer or mobile device. The app features a small collection of audio samples from the organ. The user is allowed to choose from different timbres that were deemed characteristic of the organ by experts working at the chapel. After a guided interactive tour through the history and workings of the organ, users of the app are able to play it using computer keyboard or mouse. http://www.isophonics.net/organapp/index.html