Unveiled on September 3, 2013, KitKat focused primarily on optimizing the operating system for improved performance on entry-level devices with limited resources.

Aiming for a codename that was "fun and unexpected", his team pursued the possibility of naming the release "KitKat" instead.

Lagerling phoned a representative of Nestlé, who owns the Kit Kat brand and produces the confectionery (outside the United States, where it is produced by The Hershey Company under license), and quickly reached a preliminary deal for a promotional collaboration between the two companies, later finalized in a meeting at Mobile World Congress in February 2013.

The partnership was not revealed publicly, or even to other Google employees and Android developers (who otherwise continued to internally refer to the OS as "KLP"), until its official announcement in September.

[6][7] As part of the promotional efforts, Kit Kat bars in the shape of the Android robot logo were produced, while Hershey ran a contest in the United States with prizes of Nexus 7 tablets and Google Play Store credit.

This data was used to optimize and decouple Google apps and services found to be inefficient, thus helping to reduce the overall memory usage of Android.

[13][14] The overall interface of KitKat further downplays the "Holo" interface appearance introduced on 4.0, replacing remaining instances of blue accenting with greys and white (such as the status bar icons), and getting rid of the Wi-Fi upstream and downstream traffic indicators (triangles pointing up and down), though they can still be seen in the quick control center menu.

[20] On stock devices, the Messaging and Movie Studio apps were removed; the former was replaced by Google Hangouts, which supported SMS.