
Samsung Galaxy J1
The latest firmware for Samsung Galaxy J1 (SM-J100FN) is J100FNXXU0APC1 with Android 4.4.4, released on April 1, 2016 for 16 regions (CSC). Every official firmware build for SM-J100FN, 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/J100FNXXU0APC1
All 12 builds in our database run Android 4.4.4. The newest build, J100FNXXU0APC1, was released on April 1, 2016. No new build has appeared for 128 months, so regular updates for this model have most likely ended. Builds of this model reach 16 regions (CSC); SER (Russia) usually gets a new build first (75% of recent builds).
Specifications of SM-J100H, a regional variant of the same device. Chipset and SIM lines are left out: they can differ by region.

SM-J100VPP

SM-J106M

SM-J105Y

SM-J200GU

SM-J110M
The newest firmware for SM-J100FN runs Android 4.4.4: build J100FNXXU0APC1, released on April 1, 2016.
The latest build for SM-J100FN, J100FNXXU0APC1, was released on April 1, 2016 (10 years ago).
SM-J100FN has had no new firmware for 128 months, so regular updates have most likely ended.
Yes, all firmware files for SM-J100FN are 100% official, original, and obtained directly from Samsung servers.
To flash SM-J100FN, 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-J100FN.