Im used to play on aternos with friends (java ofc). I use aternos because a random dude told me it was free, but now I know how to mod and want to add mine in the server

Problem : aternos allow only specific mods in the server so that mean you either play with the mods allowed or play with mods server sided only.

Anyone know any free Minecraft server hosting website that allow me to put in the server any custom mod I want