
Samsung Galaxy J1
The latest firmware for Samsung Galaxy J1 (SM-J100ML) is J100MLDXS0AQB1 with Android 4.4.4 (KitKat), released on February 1, 2017 for 5 regions (CSC). Every official firmware build for SM-J100ML, 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/J100MLDXS0AQB1
All 9 builds in our database run Android 4.4.4 (KitKat). The newest build, J100MLDXS0AQB1, was released on February 1, 2017. No new build has appeared for 118 months, so regular updates for this model have most likely ended.
Specifications of SM-J100MU, 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-J100ML runs Android 4.4.4 (KitKat): build J100MLDXS0AQB1, released on February 1, 2017.
The latest build for SM-J100ML, J100MLDXS0AQB1, was released on February 1, 2017 (9 years ago).
SM-J100ML has had no new firmware for 118 months, so regular updates have most likely ended.
Yes, all firmware files for SM-J100ML are 100% official, original, and obtained directly from Samsung servers.
To flash SM-J100ML, 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-J100ML.