do you know good and free obfuscation tool or software ?

never found free way to get server FUD. I use payed crypters alien by KGB 160 mo btc. Now you can go on github winRAT older edition. its in python will go through al the email systems. with this you can upload any server you want once winRAT is on the device

i've only seen tools on github to obfuscate javascript

It really depends on your language programming!
When it comes about powershell, you have ISEsteroids, when it comes about Java, you have proguard.
</br>

so there is no who can reccomend ?

FUD crypters cost money!

you need to be more specific, what is it do you need? language? objective?