Making quick changes to mobile apps in use out in the wild is a big challenge for developers. App makers often need to make these changes to respond quickly to market conditions, and to get the right content in front of the right mobile user at the right time.

That’s what Menlo Park, California-based Apptimize is all about. It’s a software-as-a-service platform upon which developers can make quick changes to native apps in real time without having to push out an update or notify the app stores.

“The example I give is that on Black Friday, some of our customers use it to change the deals in real time,” Apptimize CEO Nancy Hua told VentureBeat. “You wouldn’t be able to do that unless you had a web app; doing that with a native app would take weeks.”

And making changes doesn’t require coding skills. “It’s not just for developers; product managers, designers, and marketing people can use it,” Hua said.

Here’s the video demo:

The real-time deployment and optimization features are brand new; until recently Apptimize was focused on A/B testing and giving customers the ability to push updates users of different versions of the app.

The company today announces that it has taken a $4 million investment from Costanoa Venture Capital. The round brings Apptimize’s total funding to $6 million, after a $2.1 million seed round in January 2014.

Business has been good, Hua said. “We have a lot of major app makers as customers; we’re probably on the device you’re using right now.”

Asked for details, Hua said Hotel Tonight, Vevo, Glassdoor, and Strava are customers, as is an unnamed Top 5 ecommerce brand and a Top 10 financial services company.

“What made me excited about [Apptimize] was the ease by which we could make a change to this new app that just got launched and unlock the whole potential of building things more quickly,” Vevo senior director of product Jon Li said in a statement.