
Samsung GALAXY GRAND Prime
The latest firmware for Samsung GALAXY GRAND Prime (SM-G530AZ) is G530AZTUS4BQE2 with Android 5.1.1, released on May 11, 2017 for 1 region (CSC). Every official firmware build for SM-G530AZ, newest first: one row per build with all regions (CSC) that received it.
Each firmware build has its own page at https://samfirm.shop/build/{PDA}, where {PDA} is the build number from the list above. Example: https://samfirm.shop/build/G530AZTUS4BQE2
Specifications of SM-G530, a regional variant of the same device. Chipset and SIM lines are left out: they can differ by region.

SM-G530A

SM-G531Y

SM-G532MT

SM-G525N

SM-G6200
You can find the firmware on the model: SM-G530AZ page.
Yes, all firmware files for SM-G530AZ are 100% official, original, and obtained directly from Samsung servers.
To flash SM-G530AZ, you need to download the appropriate firmware, put your device into Download Mode, and use the Odin tool to load the BL, AP, CP, and CSC files.
Downgrading is only possible if the bootloader version (binary bit) of the old firmware matches the current one. Always check the binary version before flashing SM-G530AZ.