You don't have time to wait in a long line to get your morning caffeine fix or to grab your lunch. If only you could skip the line.

Well, there's an app for that.

More restaurants are offering free apps billed as providing greater convenience to consumers, appealing particularly to millennials who are early adopters of technology and often glued to their smartphones.

In October, McDonald's is planning a national launch for an app with coupons, joining the growing list of fast food chains offering free apps in the App Store and Google Play Store. Before the end of the year, Starbucks will have rolled out its mobile order and pay feature.

More than 25 percent of adults — 40 percent of millennials — have downloaded a restaurant app in a three-month period, according to recent survey in 2014 by Technomic, a Chicago-based food service consultant.

Not all quick-service and fast-casual places are competing on the same level when it comes to integrating technology into their restaurants.

"It's kind of the early days for most fast food restaurants. I think consumers are willing to experiment a little bit and get comfortable with the apps," said Jackie Dulen Rodriguez, senior manager at Technomic.

Some restaurants are aiming to make fast food, well, faster, including Taco Bell and Panera Bread. The restaurants enable customers to save their orders on their phones, send in the orders, pay in advance and pick up their mobile order at a designated counter, bypassing other customers.

Unless the consumer is a frequent customer, a restaurant app might not be compelling enough to give up space on their cellphones, Rodriguez said. Consumers want something in return for downloading the app on the phone, like reward points or deals, she said.