Windows 8.1 build 9600.16581

On 2014-01-08, WTZor.Net released an article that described this build. It is supposed to be a pre-release build of "Windows 8.1 2014 Update". 7 screenshots were published in the article. They also tweeted several screenshots, two of them not even included in the article.

On 2014-01-13, another screenshot was posted by Hipek to CentrumWindows ▪ forum.

Updates
This build was receiving updates.

6.3.9600.16593.winblue_s14.140103-2115
On 2014-01-15, WTZor.Net released an article that described this upload. 5 screenshots were published with the article.

On 2014-01-18, Hipek posted 3 screenshots of this build to CentrumWindows ▪ forum.

6.3.9600.16594.winblue_s14.140106-1800
This build was reported by ultrawindows. This buildstring was listed on "Is This File Safe?" website: source.