iOS 9.3 (build 13E233) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2016-03-21T18:56:24Z. The update package is 358.97 MB. This is a delta (partial) update that requires 9.0.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 0f038dccac51596dd1914ba968fa2031ebbef43b.zip.