On the web portal, users could upload Adobe Flash, HTML5/JavaScript, Shockwave, Java, and Unity games with integrated high scores and achievement badges.

Kongregate was released on October 10, 2006, by siblings Emily and Jim Greer into an alpha testing phase, which lasted until December 2006.

[2] In 2014, the site introduced digital creatures called Kongpanions, which act as a site-wide achievement system and metagame.

[10] In early 2013, Kongregate announced a $10 million fund devoted to mobile gaming,[11] and as part of this new program, the former Zynga executive Pany Haritatos was hired to oversee it.

[13] Some of the developers benefited by this fund included Synapse Games, RedPoint Labs, and Making Fun.

[citation needed] On June 20, 2017, Kongregate announced it had closed a deal to be acquired by Swedish entertainment company Modern Times Group[16] for $55 million.

[20][21] On July 1, 2020, Kongregate announced the discontinuation of submissions as it prepared for the end-of-life for Adobe Flash Player by December 31, 2020, during which time the software required to run most of its games would be disabled in some browsers.

Other features of the site such as the forums were also halted at the time as the Kongregate team worked on transitioning their internal titles to HTML5.

[23] The storefront was available via browser or desktop app and features both premium paid games and free browser-based titles.