iOS 9.3 (build 13E233) is an official Apple over-the-air update for the iPhone 6, released on 2016-03-21T18:56:31Z. The update package is 300.78 MB. This is a delta (partial) update that requires 9.2.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: b475f91d5e436943af01c3f41f2ac2a92e71308e.zip.