Cydia is a computer program for the mobile operating system, Apple iOS, which allows the user to browse and download software and tweaks for iPhone, iPod Touch, Apple TV or iPad. The condition is that its firmware was modified with the help of a so-called jailbreaks so that software not only - as standard provided - from the Apple App Store by the manufacturer, but can also be installed from any other sources. Cydia by Jay Freeman was (also known as saurik ) and his company SaurikIT, LLC develops and originally released as open - source alternative to on iOS 1.1.x. It evolved from approximately the firmware version 2.x quickly become the most popular package manager. Most jailbreak programs on how to unlock iOS devices to install Cydia is already provided by default.

Cydia provides a user- friendly graphical interface for some open-source software - installation tools originally for Debian ( specifically APT and dpkg package management system ) developed. Cydia repositories allow the installation of software packages, most of which can be downloaded for free. Cydia also includes the Cydia Store, in which a series of treatments are available for sale. Both the free and the paid software packages are downloaded directly to an iOS device and at the same point of the file system (Applications folder) as the pre-installed applications from Apple installed. For buying a user account must be set up for payment under other PayPal.

In September 2010 SaurikIT, LLC bought the competitor Rock Your Phone, Inc. All Apps, users and licenses were transferred to the Cydia Store.