The latest stable version, 5.7.1 , supports multiple SA-MP versions including 0.3.7-R1, R3-1, R5, and 0.3.DL.

Many modern "advanced" mods and cheats require SAMPFUNCS to function, as it acts as the bridge between the mod and the game's internal data. How to Install SAMPFUNCS.asi

For developers, the SAMPFUNCS Wiki provides a full SDK and change history to help you build your own custom plugins.

You can find the official distribution of SAMPFUNCS on BlastHack, the primary hub for the project.