In 2013, apps are expected to generate $25 billion in revenue, according to a March forecast from ABI Research, which tracks mobile application trends. The popularity of tablets over smartphones is also expected to increase demand for apps, and developers who make apps with devotional or religious themes see potential to expand their audiences.

Christian publishers who have been exploring ways to extend authors’ reach have augmented print materials with apps offering interactive features that allow readers to learn more about hyperlinked words or take digital notes on their mobile devices. Developers working independently of book publishers have started creating faith-related apps to commemorate holidays and anniversaries, or to create communities of people interested in spiritual practices like meditation or Bible study.

Clear winners for publishing-related apps are those that complement children’s titles. Gary Chapman, author of the perennially bestselling The 5 Love Languages (Moody Publishers) recently released a children’s title, A Perfect Pet for Peyton. Janis Backing, publicity manager at Moody, says that creating an app for it drove a rise in sales. “Since this is our first app, we don’t have anything else to compare it to, but the feedback we’ve received from readers is they’re very pleased with the book, the story, and the way the app enhances the story,” she says.

Molly Kempf Hodgin, director of new media for children’s and gift books at Thomas Nelson, says that apps for bestsellers like Jesus Calling and Max Lucado’s Live Loved have been successful among consumers, with Bible study and devotional applications that allow users to highlight passages on a tablet while on the go in a way that isn’t as common with print copies anymore, she notes. The ease with which apps are shared as gifts has also helped.

Outside of Christian publishing, developers with faith-specific interests have experimented with creating applications for niche audiences. Brad Fullmer, owner of Spotlight Six Software, got his first iPhone in 2008. As a meditator, he noticed that while he liked the new phone, its timer sounds weren’t particularly pleasant. He created Insight Timer, an application that allows meditators worldwide to set any amount of meditation time they’d like, while also viewing a map of other meditators around the globe. “The whole idea behind the app at first was to make a basic kind of timer—instead of having a nasty buzzing sound, [it’s] a beautiful bell.” More than four years later, the app is available across operating systems for $1.99 and has logged over three million meditation sessions. Fullmer has added group features that offer forums so that people can meditate in virtual groups.

Sam Tannen, an independent developer based in Los Angeles, creates children’s content through his company, Corky Portwine. He’s made a Hanukkah app in the past—such avenues for Jewish storytelling didn’t exist in his youth—but when his father mentioned that Passover was approaching, he developed Passover: The Ten Plagues, which he says has been his most popular app to date. He credits that to practice (he’s developed several other apps for children) and timing. “Explaining it to people is a challenge,” Tannen says. “I call it an interactive storybook, or a digital animated storybook. It’s easier just to show people.”

Other developers have been making holiday-related applications for adults as well. Downhill publishing released the Ultimate Digital Haggadah 2.0, offering readers an illuminated copy of the ancient text for Passover Seder dinners. Recognizing that they have a new opportunity to reach readers with illuminated text, some religious magazine publishers are getting into the app market, too. In March, the Roman Catholic magazine Liguorian announced an app for iPads, iPhones, and the iPod Touch to debut for users with the 100th anniversary issue of the magazine. Users of the Liguorian app could download the issue for free.

Catholic publishers like Our Sunday Visitor have also started creating apps; several give easier access to content about saints from the book Our Sunday Visitor’s Encyclopedia of Saints, says Greg Pike, director of publishing operations. The most popular among them is Saint Names for Your Baby, though there is also a rosary app and an app for patron saints. Pike says that Our Sunday Visitor has intentionally avoided “dumping a book into an app.” Instead, he is aware that “as publishers, we’re all competing for time and attention. Some people fire up Facebook [on their phones], but others spend time connecting deeply with what they believe in.”