Mass-online.org is an Android application developed by Marek Rzewuski Best Online. It is a free app under the Social & Communication category, offering the ability to watch Holy Masses online from different parishes worldwide. The app presents a calendar with Catholic Holy Masses that are live online. By clicking on the chosen hour and the link "Watch online Holy Mass," users can easily stream the Holy Mass online in English.

The app is a convenient way for users to participate in Holy Masses from the comfort of their own home or while traveling. The interface is user-friendly, and the app is easy to navigate. The app also provides a way for users to stay connected with their faith and community even when they are unable to attend Mass in person. Overall, Mass-online.org is a useful app for Catholic users looking to watch Holy Masses online.