
Samsung Galaxy J1
The latest firmware for Samsung Galaxy J1 (SM-J100F) is J100FXXU0APB1 with Android 4.4.4, released on April 26, 2016 for 7 regions (CSC). Every official firmware build for SM-J100F, 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/J100FXXU0APB1
All 20 builds in our database run Android 4.4.4. The newest build, J100FXXU0APB1, was released on April 26, 2016. No new build has appeared for 127 months, so regular updates for this model have most likely ended.
Specifications of SM-J100H, a regional variant of the same device. Chipset and SIM lines are left out: they can differ by region.

SM-J327VPP

SM-J100VPP

SM-J260A

SM-J120P

SM-J737A

SM-J727A

SM-J727VPP

SM-J327A
The newest firmware for SM-J100F runs Android 4.4.4: build J100FXXU0APB1, released on April 26, 2016.
The latest build for SM-J100F, J100FXXU0APB1, was released on April 26, 2016 (10 years ago).
SM-J100F has had no new firmware for 127 months, so regular updates have most likely ended.
Yes, all firmware files for SM-J100F are 100% official, original, and obtained directly from Samsung servers.
To flash SM-J100F, 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-J100F.