iOS 9.3 (build 13E237) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2016-03-28T16:52:44Z. The update package is 1.04 GB. This is a delta (partial) update that requires 8.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 92c40b596ca9ebcedb285f073a41ce4694a8792d.zip.