iOS 8.3 (build 12F70) is an official Apple over-the-air update for the iPhone 5c (GSM), released on 2015-04-08T17:56:13Z. The update package is 397.26 MB. This is a delta (partial) update that requires 8.0.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 137e0f812f08400e5e8f6143a78826f79e63bb5b.zip.