Before downloading any firmware, you must confirm your exact model number. Flashing the wrong firmware can permanently damage ("brick") your device.
Developers at XDA-Developers ported the KitKat firmware from the 2GB Korean variant to the standard I9300. s3 firmware update 4.4 download
This 2GB RAM variant received official KitKat 4.4.x updates in many regions. Official Firmware Download for S3 Neo (GT-I9300I) Before downloading any firmware, you must confirm your
This model (1GB RAM) officially supports up to Android 4.3. Android 4.4 is only available via community-ported ROMs. This 2GB RAM variant received official KitKat 4
Once you have downloaded the .tar.md5 firmware file, follow these steps to flash it:
Sites like AndroidFileHost host unofficial builds like SlimROM (4.4.4) for the I9300. Installation Guide Using Odin
Since Samsung officially denied the 4.4 update for the standard I9300 due to its 1GB of RAM, you must use unofficial ports: