iOS 8.4 (build 12H143) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2015-06-30T15:51:21Z. The update package is 1.02 GB. This is a delta (partial) update that requires 7.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 2f1673260f69c73c2ab43247059a21093d695762.zip.