I want to open a zombie survival server, would anyone have a free base ??
To FiveM
There are a few codebases you can start with on github.
Zombie Survival Roleplay
https://github.com/n0yzcl/fivem-zsr
CorruptSnail (successor to RottenV)
https://github.com/FiveM-Scripts/CorruptSnail-Gamemode
blurrdev
https://github.com/n0yzcl/BruZe
Hope that helps.