iOS 9.3 (build 13E237) is an official Apple over-the-air update for the iPhone 4s, released on 2016-03-28T16:52:18Z. The update package is 254.44 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: c94f64483e6adc07a17aa26cf88ffad3dfba22b0.zip.