Use when implementing client-server communication in Roblox, firing events between LocalScripts and Scripts, passing data across the network boundary, syncing game state, or defending against exploits that abuse RemoteEvents or RemoteFunctions.

Roblox Remote Events & Functions RemoteEvent vs RemoteFunction Type Direction Returns value? Use when RemoteEvent Any direction No (fire and forget) Notifying server of player action, broadcasting state RemoteFunction Client→Server Yes (yields caller) Client needs a result back (e.g. fetch inventory) UnreliableRemoteEvent Any direction No High frequency updates where dropped packets are fine Default to RemoteEvent. Avoid server→client RemoteFunction — an exploiter's frozen callback stalls your server thread indefinitely. Where to Put Remotes Always store Remotes in ReplicatedStorage . Create them from a server Script that runs before any LocalScript. Firing Patterns Client → Server (FireServer) Server → One Client Server → All Clients RemoteFunction (Client Calls, Server Returns) UnreliableRemoteEvent (High Frequency Sync) CRITICAL: Server Side Security The client is hostile. Treat every argument as untrusted input. Exploit Patterns & Defenses Exploit What the attacker does Defense Argument injection Sends unexpected types to crash handler Type check all arguments Damage amplification Sends amount = math.huge Clamp to sane maximum Remote spam Fires thousands of times per second Per player cooldown Spoofed target Sends another player's UserId Server resolves from its own state Infinite yield Never returns from OnClientEvent callback Avoid server→client RemoteFunction Duplicate action Replays a valid fire to buy twice Check state / consume token before acting Quick Reference Common Mistakes Mistake Fix OnServerEvent in a LocalScript Use OnClientEvent on client; OnServerEvent is server only Remotes in ServerStorage Move to ReplicatedStorage Trusting payload beyond player identity Validate every field in the payload Server→client RemoteFunction Use RemoteEvent; frozen client stalls server thread No WaitForChild in LocalScript Remotes may not exist yet; always use WaitForChild Multiple OnServerInvoke assignments Only the last assignment wins; keep it in one place Firing inside tight loop without throttle Use UnreliableRemoteEvent or accumulate delta time

roblox-remote-events