Samsung Galaxy S 3 (International) (GT-I9300) Firmware Overview
What is the latest GT-I9300 firmware?
I9300XXUGPE1, released August 9, 2016 for region AMN with Android 4.3. The archive holds 2 official builds for this region.
Is the Samsung Galaxy S 3 (International) still getting updates?
Most likely not: there has been no new firmware since August 2016, so Android 4.3 is the last version this model got. The final builds below are still the best choice for a clean reinstall.
GT-I9300 firmware for region AMN
How to Flash GT-I9300 Firmware
Put the Samsung Galaxy S 3 (International) into Download Mode, load the BL, AP, CP and CSC files into Odin on a Windows PC and press Start. Use HOME_CSC to keep your data, CSC for a full wipe.