A roblox custom anti cheat script is usually the first thing developers start looking for the second they notice their game is gaining any kind of real traction. It's a bit of a bummer, but that's the reality of the platform—as soon as you have a few hundred concurrent players, someone is going to try to break your game. Whether it's flying across the map, walking through walls, or suddenly having infinite money, exploiters can ruin the experience for everyone else in a matter of seconds. While Roblox has its own built-in protections like Hyperion, those are mostly designed to stop the "injectors" themselves. They don't always catch the specific, game-breaking logic that's happening inside your specific world. That's where your own custom script comes into play.
Building a roblox custom anti cheat script isn't just about writing a few lines of code and calling it a day. It's more like a constant game of cat and mouse. You build a wall, they find a ladder; you take away the ladder, they find a trampoline. But don't let that discourage you. A well-made custom script can stop 95% of the "script kiddies" who are just downloading free exploits and trying to act cool. You don't need to be a coding genius to start, but you do need to change the way you think about how your game communicates with the players.
The Golden Rule: Never Trust the Client
If you take away nothing else from this, remember this one thing: the client is a liar. In Roblox terms, the "client" is the player's computer, and the "server" is the master computer running the game. Anything that happens on the client can be manipulated. If you put your roblox custom anti cheat script inside a LocalScript and tell it to kick the player if they go too fast, the exploiter can just delete that script. Or, they can disable it. Or, they can rewrite the "kick" function so it does nothing.
Because of this, your anti-cheat logic almost always needs to live on the server. You want a Script in ServerScriptService that's watching the players from a distance. The server sees the truth (mostly). If the server sees a player move from Point A to Point B in 0.1 seconds when it should take 10 seconds, the server knows something is up. It doesn't matter what the client says; the server makes the final call.
Detecting Speed and Fly Hacks
The most common exploits you'll deal with involve movement. Everyone wants to go fast or fly. A basic roblox custom anti cheat script usually starts by monitoring the HumanoidRootPart of every player. You can set up a loop that checks a player's position every second. If the distance between their current position and their last recorded position is physically impossible given their WalkSpeed, you've caught them red-handed.
However, you have to be careful about lag. We've all been in games where we're lagging so hard we practically teleport across the room. If your script is too aggressive, you're going to end up kicking players who just have a bad internet connection. To fix this, most developers use a "violation" system. Instead of kicking them immediately, you give them a point. If they get 5 "violation points" in a minute, then you kick them. This gives legitimate, laggy players a bit of breathing room while still catching the guy who's zooming across the map at 500 studs per second.
Securing Your Remote Events
This is where things get a bit more technical, but it's arguably the most important part of any roblox custom anti cheat script. RemoteEvents are the "telephones" that let the client talk to the server. For example, when a player clicks a button to buy a sword, the client sends a message through a RemoteEvent saying, "Hey server, I'm buying this sword."
If you don't secure these, an exploiter can just fire that event 10,000 times a second. Suddenly, they have 10,000 swords and you have a crashed server. You need to implement what we call "sanity checks." When the server receives that "buy" request, it needs to check: 1. Is the player actually near the shop? 2. Do they have enough money? 3. Have they already sent a request in the last half-second?
If the answer to any of those is "no," you ignore the request. You'd be surprised how many games forget to check if a player is actually standing near an item they're trying to interact with. If your script doesn't check the distance, a player can sit at the spawn point and "click" every treasure chest on the entire map remotely.
Watching for Noclip and Wall Hacks
Noclipping—where players walk through solid objects—is a bit trickier to detect. Usually, exploiters do this by deleting the "CanCollide" property on parts locally. Since the server still thinks the wall is solid, it won't automatically stop them.
One way to handle this in your roblox custom anti cheat script is to use Raycasting. You can occasionally cast a ray between a player's previous position and their current position. If that ray hits a wall that's supposed to be solid, it means the player just moved through an object they shouldn't have been able to. Again, you don't want to do this every single frame because it'll tank your server performance, but doing it every few seconds for each player is usually enough to catch people trying to skip levels or sneak into restricted areas.
Protecting Your Values
Don't ever store important stuff like "Gold" or "Level" inside the player's folder in the Workspace. Exploiters can see everything in the Workspace. Instead, keep your data in ServerStorage or a folder in ReplicatedStorage that is only modified by the server.
When you're writing your roblox custom anti cheat script, you should treat the player's leaderstats as a display only. The real math should happen behind the scenes on the server. If a player somehow manages to change their "Coins" value on their screen to a billion, it shouldn't matter because the server knows they actually only have ten. When they try to spend that billion, the server-side sanity check will look at its own record, see the ten coins, and deny the transaction.
Dealing with False Positives
There is nothing that kills a game's vibe faster than getting kicked for "cheating" when you weren't doing anything wrong. This happens a lot with physics-based games. If a player gets hit by a car or an explosion and gets launched across the map, a simple speed check might think they're teleporting.
To prevent this, your roblox custom anti cheat script needs to be aware of the game's state. If a player just took damage or was recently in a vehicle, you might want to temporarily pause the movement checks for them. It's better to let a cheater get away with it for five seconds than to kick five innocent players who just happened to get caught in a physics glitch. Always lean on the side of caution.
The Importance of Logging
Don't just kick people silently. You want to know why they were kicked. A good roblox custom anti cheat script should log everything to a private Discord channel using Webhooks or a data store. If you see that 50 people were kicked in one hour for "Speeding," but they were all in the same area, you might have a bug in your map that's flinging people, rather than a sudden wave of hackers.
Logging also helps you identify the "whales" of the exploiting world—the people who keep coming back with new accounts. If you see the same patterns, you can start looking into more advanced bans, like Datastore-based bans that persist even if they change their username.
Keeping Your Script Updated
Exploiters are surprisingly dedicated. They have forums, Discord servers, and entire communities dedicated to breaking Roblox games. If you find a "free" roblox custom anti cheat script online, chances are the exploiters have already seen it and found a way around it.
The best anti-cheat is one you've customized specifically for your game's mechanics. If your game doesn't have a double-jump mechanic, then your script should be very suspicious of anyone who stays in the air for more than a second. If your game doesn't have vehicles, then anyone moving faster than the default 16 studs per second is a red flag. The more "game-specific" your checks are, the harder they are for generic exploits to bypass.
At the end of the day, you'll never stop 100% of exploiters. It's just not possible on a platform like Roblox. But by implementing a solid roblox custom anti cheat script, you make it so difficult and annoying for them that they'll usually just give up and move on to an easier target. Your goal isn't to be an impenetrable fortress; it's just to be a harder nut to crack than the game next door. Keep your logic on the server, check your remotes, and always, always assume the client is lying to you.