Kourtney Kardashian is the only one of the Kardashian and Jenner sisters whose app hasn’t gone live. That’s left fans wondering why.

Mom Kris Jenner dished about the upcoming app during a recent interview with Entertainment Tonight.

“Kourtney’s will be live next month,” the Keeping Up With the Kardashians matriarch says. “The girls have been working around the clock for a year on their apps and sites, and Kourtney gave birth to Reign in December. While everyone else was deep in production, she was taking time with her infant, nursing and caring for her children. So, she’s a little behind, but, it is going to be fabulous.”

EXCLUSIVE: @KrisJenner reveals why @KourtneyKardash is the only sister without her own app. http://t.co/yOQeLUtUVt pic.twitter.com/wQwOpJSIQe

— EntertainmentTonight (@etnow) September 15, 2015

At Apple’s “Meet the Developer” event in New York City on Monday, Kourtney Kardashian stunned in tight black leather pants and a matching leather bandeau. She attended the event with her sisters and teased what her new app will feature.

“Mine is more curated,” she said. “I’m obsessed with interior design, so it’s a lot about that. I’m obsessed with being a mom. I have very specific ways of being a mom, as well.”

“All my friends come to me with mom questions, so just sharing my favorite things,” Kourtney Kardashian added. “There’s not one thing on [my app] that I’m not obsessed with thoroughly.”

NYC night vibes. pic.twitter.com/5NqyX8E5ql

— Kourtney Kardashian (@kourtneykardash) September 15, 2015

Kylie Jenner was quick to sing the praises of Kourtney Kardashian’s app.

“Her app’s going to be amazing. She loves being a mom,” Kylie said. “She’s spent a little more time on it.”

The purpose of these apps the Kardashian and Jenner sisters have created is to allow fans more insight into each of their lives.

Kylie Jenner was eager to boast about her own app, too.

“Everyone wants to see, like, my makeup tips, and what I do with my hair, and this and that,” Kylie Jenner said. “So I just wanna do, like, tutorials, and what I use, because I feel like people are really interested in that.”

Hmm… Why doesn't @kourtneykardash have her own app? http://t.co/41lwzcAWZJ pic.twitter.com/B4fVOsrO7z

— cambio (@cambio) September 17, 2015

Kourtney Kardashian’s new app–as well as those of the other Kardashian and Jenner sisters–costs $2.99 per month, and may be purchased in the app store at iTunes.com.