iPadOS 8.4 (build 12H143) is an official Apple over-the-air update for the iPad 4 (WiFi), released on 2015-06-30T15:51:11Z. The update package is 301.77 MB. This is a delta (partial) update that requires 8.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 6d932d7fd9a2f341992cb1a0614577ff86e4a82e.zip.