Custom Chat Server Script

local chat = game:GetService("Chat")
local rep = game:GetService("ReplicatedStorage")
local event = rep:WaitForChild("Chatted")

local format = "[%s]: %s"
event.OnServerEvent:Connect(function(Player,String)
    if typeof(String) == "string" then -- check if string
        local bool,result = pcall(function()
            return chat:FilterStringForBroadcast(String,Player) -- filter
        end)

        if bool then
            event:FireAllClients(string.format(format,Player.Name,result)) -- send filtred string
        end
    end
end)