Putting together a solid roblox anti exploit script server side is probably the single most important thing you'll do for your game's longevity. If you've spent any amount of time in the Roblox developer community, you've definitely heard the phrase "never trust the client." It's basically the golden rule, but honestly, it's easier said than done when you're just trying to get your game to run smoothly. The reality is that if you leave your security to local scripts, you're essentially handing the keys to your game over to anyone with a basic executor.
Let's break down why the server-side approach is the only one that actually matters. When a player joins your game, they have full control over what happens on their own computer. They can delete scripts, change variables, and manipulate their character's local environment. However, they don't have that same power over the server. By shifting your logic and security checks to the server, you create a barrier that most exploiters simply can't jump over.
Why the client is a liar
Think of the client (the player's computer) as a witness in a courtroom who has a very strong reason to lie. If that witness tells you they just walked across the map in 0.5 seconds, or that they suddenly have a billion coins, you shouldn't just take their word for it. In the world of Roblox, exploiters use tools to inject code that tells your game exactly these kinds of lies.
If you put your anti-cheat logic in a local script, the exploiter can see it, disable it, or just rewrite it to return "true" every time it checks if they're cheating. That's why a roblox anti exploit script server side is your only real line of defense. The server is the "Source of Truth." It decides what actually happened and what didn't.
Securing your RemoteEvents
RemoteEvents are usually where things go wrong for new developers. They're the bridge between the client and the server, and if that bridge isn't guarded, exploiters will drive a tank right across it. Let's say you have a RemoteEvent called GiveGold. If a local script fires that event and the server just mindlessly hands out gold, an exploiter is going to spam that event until your game's economy is in the trash.
Instead of the client telling the server "Give me 100 gold," the client should tell the server "I just finished this quest." Then, the server checks if the quest was actually active, if the player was near the quest NPC, and if they haven't already claimed the reward. This is what we call a "sanity check." It's about making sure the request actually makes sense within the context of the game.
Handling movement and speed hacks
Movement exploits like speed hacking, flying, and teleporting are incredibly common because they're easy to pull off on the client side. Since Roblox handles physics locally to make movement feel smooth, the server often trusts where the player says they are. To stop this, you need a server-side script that monitors player positions over time.
You can do this by checking the distance between a player's current position and their last known position. If they moved 500 studs in a single heartbeat, and your max walk speed is 16, something is obviously wrong. You don't necessarily want to kick them immediately—sometimes lag happens—but you should definitely teleport them back to their previous valid location. This makes speed hacking essentially useless without ruining the experience for players with a bad internet connection.
Protecting your game's economy
DataStores and currency are high-value targets. If your game has a shop, never let the client tell the server how much an item costs. I've seen so many games where the client sends a request like BuyItem(itemName, price). An exploiter can just change that price to -999999 and suddenly they're "buying" items and gaining money at the same time.
Your server-side script should have a master list of item prices. When the client says "I want to buy the Dragon Sword," the server looks up the price in its own internal table, checks the player's balance on the server, and only then deducts the money and grants the item. It's all about keeping the important math away from the player's reach.
Common pitfalls with server-side checks
One mistake I see a lot is over-correcting. If your server-side checks are too strict, you'll end up punishing players for having a high ping. For example, if your "anti-teleport" script is too sensitive, a player who lags for two seconds might get snapped back across the map or kicked for "exploiting" when they were just trying to walk through a door.
It's usually better to be a little bit lenient. Instead of checking every single frame, check every second. Instead of checking for a 1-stud discrepancy, check for a 20-stud discrepancy. You aren't trying to stop every tiny micro-cheat; you're trying to stop the game-breaking stuff that ruins the experience for everyone else.
The importance of rate limiting
Exploiters love to spam. Whether it's firing a RemoteEvent to spawn an item or trying to trigger a dialogue system, they'll do it as fast as their computer allows. This can not only break your game logic but also lag the server for everyone else.
Implementing rate limiting in your roblox anti exploit script server side is a lifesaver. Keep a table on the server that tracks when each player last fired a specific event. If they fire it again within 0.1 seconds and the event should only happen once every 5 seconds, you just ignore the request. You can even log how many times they've triggered the rate limit and flag them for review if they're being particularly aggressive.
Sanity checks for combat and tools
If your game involves swords or guns, you've got to be extra careful. A common exploit is the "kill all" script, where an exploiter fires a damage event for every player in the server at once. To prevent this, your server script should always check the distance between the attacker and the victim.
If a player is swinging a sword but the person they "hit" is 300 studs away, the server should simply refuse to register the damage. Similarly, if a player is firing a gun, the server should perform a raycast to see if there's actually a line of sight between the shooter and the target. This won't stop a really determined aimbotter, but it will stop the most blatant and annoying types of combat exploits.
Making it harder to reverse engineer
While most of your heavy lifting happens on the server, you can still do things on the client to make an exploiter's life miserable. You can give your RemoteEvents confusing names or change them periodically. You can add "honeypot" events that do nothing but signal the server to ban whoever fired them.
However, never rely on these as your main defense. They're just "security through obscurity." A smart exploiter will figure them out eventually. Your primary focus should always remain on the server's logic. If the server is secure, it doesn't matter how much the exploiter messes with their own client; they simply won't be able to impact the game world in a way that matters.
Final thoughts on server-side security
At the end of the day, building a roblox anti exploit script server side is a bit of a cat-and-mouse game. As you close one door, someone might find a window. But by following the principle of never trusting the client and performing rigorous sanity checks on the server, you make your game a much harder target.
Most exploiters are just kids using scripts they found online. If those scripts don't work because your server is checking their math and their movement, they'll usually just move on to an easier target. Stay consistent, keep your code organized, and always ask yourself: "Could a player fake this information?" If the answer is yes, then that logic belongs on the server.