The Chaos Communication Congress is an annual conference organized by the Chaos Computer Club. The congress features a variety of lectures and workshops on technical and political issues related to security, cryptography, privacy and online freedom of speech. It has taken place regularly at the end of the year since 1984, with the current date and duration established in 2005. It is considered one of the largest events of its kind, alongside DEF CON in Las Vegas.

The Chaos Computer Club (CCC) is Europe's largest association of hackers with 7,700 registered members. Founded in 1981, the association is incorporated as an eingetragener Verein in Germany, with local chapters in various cities in Germany and the surrounding countries, particularly where there are German-speaking communities. Since 1985, some chapters in Switzerland have organized an independent sister association called the Chaos Computer Club Schweiz (CCC-CH) instead.