He compared the relationship between YouVersion and traditional publishers to the “freemium” strategy common in mobile games where the core content is free, but extra features cost money. In this case, those extras are things like devotional Bibles, study Bibles or gold-embossed heirloom Bibles.

As YouVersion became increasingly popular, other publishers also came to view the app as a positive force — less a threat than a marketing opportunity. Although there are no ads on the app and no plans to create any, Mr. Gruenewald said, YouVersion collects vast amounts of data on Bible readership patterns. That trove of data provides valuable information about the habits and preferences of Christians that YouVersion selectively shares with its traditional publishing partners, such as which verses are the most popular within their own translations.

Today, the app contains everything from the New International Version to “The Message,” an ultramodern interpretation that reads like a juicy novel. It also includes the so-called Orthodox Jewish Bible, which was actually developed for a religious sect known as Messianic Jews, who believe that Jesus is the Messiah that the Jews await.

And it has become a platform for evangelical leaders like Rick Warren to reach millions of people with custom reading plans; the pastor Billy Graham is the most recent addition. On Sunday mornings, as pastors around the country preach from iPads while congregations click on Corinthians, YouVersion’s servers track more than 600,000 requests every minute.