Since the very earliest days of jailbreaking, Cydia has been the go-to source for jailbreak-specific tweaks and apps. What makes tweaks work is the Cydia Substrate, low-level software written by Cydia founder Saurik that lets third-party programmers hook into the iOS operating system in ways not endorsed by Apple. But Cydia Substrate is closed-source, which makes it harder for alternative jailbreak stores to compete with Cydia.
That could soon change, though. Jailbreak superstar Comex — the developer of JailbreakMe, and a former programmer at Apple — is working on an alternative to Cydia Substrate.