iOS 8.3 (build 12F70) is an official Apple over-the-air update for the iPhone 6, released on 2015-04-08T17:56:16Z. The update package is 487.36 MB. This is a delta (partial) update that requires 8.1.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 91c5725025e9c6911e91a5e0e5093ff1ea474fa1.zip.