Cydia is the wildly popular alternative to Apple’s app store. It was created by Jay Freeman back in 2008 to improve an iPhone user’s experience. Since its release, thousands of developers around the world have released countless extensions and cydia apps to make using your iPhone more enjoyable.
Although you can’t actually download cydia, you can hire a knowledgeable company with experience in jailbreaking iPhones to jailbreak your phone, and once this process is complete, cydia will be installed on your phone.
Unfortunately, you can’t download cydia from the app store. It is only available on your apple device after it has been jailbroken.