ScriptHookV: 
http://www.dev-c.com/gtav/scripthookv

ScriptHookVDotNet
https://www.gta5-mods.com/tools/scripthookv-net

don't forget their requirements:
Microsoft .NET Framework 4.5(or 4.5.2)
https://www.microsoft.com/en-us/download/details.aspx?id=30653

Microsoft Visual C++ Redistributable Package for Visual Studio 2013 (x64)
https://www.microsoft.com/en-us/download/details.aspx?id=40784

NativeUI.dll
http://gtaforums.com/topic/809284-net-nativeui/

iFruitContacts.dll
http://gtaforums.com/topic/812301-net-ifruitcontacts/
