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 149 MB. 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: bdc3065f0946fbfdc32aeddcd6f49ca1fdcb89e4.zip.