iOS 9.3 (build 13E233) is an official Apple over-the-air update for the iPhone 6+, released on 2016-03-21T18:56:28Z. The update package is 1.36 GB. This is a delta (partial) update that requires 8.1.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 23a59772f78c76aeec684e2429d0b1bd0bf2231a.zip.