Here are the direct download links for iOS 8.3 firmware file:
iPad:
- iPad Air 2 (6th generation WiFi)
- iPad Air 2 (6th generation Cellular)
- iPad Air (5th generation WiFi + Cellular)
- iPad Air (5th generation WiFi)
- iPad Air (5th generation CDMA)
- iPad (4th generation CDMA)
- iPad (4th generation GSM)
- iPad (4th generation WiFi)
- iPad mini (CDMA)
- iPad mini (GSM)
- iPad mini (WiFi)
- iPad mini 2 (WiFi + Cellular)
- iPad mini 2 (WiFi)
- iPad mini 2 (CDMA)
- iPad mini 3 (China)
- iPad mini 3 (WiFi)
- iPad mini 3 (Cellular)
- iPad 3 Wi-Fi (3rd generation)
- iPad 3 Wi-Fi + Cellular (GSM)
- iPad 3 Wi-Fi + Cellular (CDMA)
- iPad 2 Wi-Fi (Rev A)
- iPad 2 Wi-Fi
- iPad 2 Wi-Fi + 3G (GSM)
- iPad 2 Wi-Fi + 3G (CDMA)
- iPhone 5 (CDMA)
- iPhone 5 (GSM)
- iPhone 5c (CDMA)
- iPhone 5c (GSM)
- iPhone 5s (CDMA)
- iPhone 5s (GSM)
- iPhone 6
- iPhone 6 Plus
- iPhone 4s
