Universalis (Universalis Publishing, iOS/Android: $14) may be my most used app. A lot of people have different tools to pray their hours or get their mass readings. I bought a Universalis PC codeyears ago and have used the offline, app version ever since. Before I had a tablet and a smartphone, I’d turn the months into epubs and send them to my Kindle. Now, everything is in one place on both phone and pad.
I prefer it to other options, for reasons partly functional and partly aesthetic. I like the way it looks and works: the text and page options, page turning, and selection features.
The Hour are all in the app with no need for a connection, and you can go as far back or forward as you like. It puts every page of the Hours on your device with a total overhead of 13 MB, and allows you access them with a discrete pair of menus: one for day, another for hour/reading.
The text includes both the NAB and the Jerusalem Bible (the one I use) with an option for the Grail psalms (ditto). It has all 7 hours: Morning (Lauds), Terce, Sext, None, Evening (Vespers), and Night (Compline). It also has the Office of Readings, Mass readings, and text of the mass, with optional prayers for priests. There are notes on the saints of the day, and liturgical calendars for US, UK, Canada, Australia, New Zealand, and more. There’s also an option to set up an email service to send particular pages every day.
I know many just use free apps for this, and that’s fine. Since I bought a code from Universalis, my app was free, but I still think I’d get it if I had to pay the $14. They issue regular updates, maintain a clean text, and do a lot of work to get this material out there free on the web. I don’t mind kicking back a little to pay them for their efforts.