If you've spent any time at all in the developer forums lately, you'll know that creating a roblox custom security library script is one of those things that separates the hobbyists from the people who actually want their games to stay playable. It's a bit of a cat-and-mouse game, really. You build something cool, someone finds a way to break it, and then you have to figure out how to patch that hole without ruining the experience for everyone else.
The reality is that Roblox is a massive platform, and because it's so accessible, it attracts a lot of people who just want to mess with things. If you're relying solely on the default settings or some old, recycled anti-cheat you found in the toolbox, you're basically leaving your front door unlocked. A custom security library isn't just about stopping exploiters; it's about creating a solid foundation for how your game handles data and communication.
Why you can't just rely on the defaults
Don't get me wrong, Roblox has actually done a decent job over the last few years improving their internal security, but they can't account for every specific game mechanic you invent. When you write a roblox custom security library script, you're essentially making a bespoke suit for your game's logic.
The biggest issue with "off-the-shelf" security solutions is that they're predictable. If an exploiter knows exactly what script you're using because it's a popular open-source one, they've already got the blueprint to bypass it. By writing your own library—usually as a series of ModuleScripts tucked away in ServerStorage—you're introducing an element of the unknown. They can't easily find the "off switch" if they don't know where you've hidden the logic.
The golden rule of server-client communication
If you take nothing else away from this, remember that the client is a liar. That's the mantra of every seasoned Roblox dev. Anything happening on the player's computer can be manipulated. This is why your roblox custom security library script needs to live almost entirely on the server.
I've seen so many new developers put their anti-exploit logic in a LocalScript inside StarterPlayerScripts. That's like asking a thief to please not rob you while you're out of the house. They can just delete the script, disable it, or hook the functions to return whatever values they want. Your security library should be the "source of truth" on the server, constantly double-checking what the clients are reporting.
Handling RemoteEvents with care
RemoteEvents are usually where the trouble starts. They're the bridge between the player and the server. If you have a RemoteEvent called "GiveGold," and you don't have a security library checking it, someone is going to fire that event 10,000 times a second and break your economy.
In your custom library, you should have a central function that handles all incoming remote traffic. Instead of just accepting a value, your script should ask questions: * Did this player fire this event too fast? (Rate limiting) * Is the value they sent even possible? (Sanity checking) * Is the player close enough to the object they're trying to interact with? (Distance checking)
Building the core "Sanity Check" modules
A good roblox custom security library script should be modular. You don't want one giant, messy script that's impossible to debug. I like to break mine down into specific categories like "Movement," "Economy," and "Combat."
For movement, you're looking for things like teleportation or fly hacks. You can't just check the player's position once; you have to track it over time. If a player was at point A a second ago and is now at point B, which is 500 studs away, and they don't have a "Teleport" power-up active, your library should flag that. But you have to be careful—lag happens. You don't want to kick a kid just because their internet dipped for a second and they "rubber-banded" across a room. A good library uses a "strike" system rather than an instant ban.
Combat and damage validation
Combat is another huge area for exploitation. Kill-all scripts or reach hacks can ruin a fighting game in seconds. When a player "hits" another player, the client should send the signal, but the server-side library should be the one to actually calculate the damage.
It should check if the player even has a weapon equipped, if the target is within a reasonable distance, and if the weapon is actually cooled down. If the library sees a player dealing damage with a sword while their character is halfway across the map, it can just ignore that request entirely.
Obscurity and Evasion
While "security through obscurity" isn't a complete solution, it definitely helps. When you're naming things in your roblox custom security library script, don't name your remote events things like "AdminBanEvent" or "KillPlayer." That's just giving exploiters a map.
Some developers go as far as to give their remotes random strings of characters as names that change every session, though that can be a headache to manage. At the very least, keep your sensitive logic inside ServerStorage or ServerScriptService. These folders are never replicated to the client, meaning an exploiter can't even see the code you're using to catch them. They're essentially fighting a ghost.
The importance of performance
One thing people forget when they're getting deep into security is that every check takes a tiny bit of processing power. If you're running a thousand checks every frame for every player in a 50-person server, you're going to kill your server's performance.
Your roblox custom security library script needs to be efficient. You don't need to check for fly hacks every single frame. Checking once every half-second or even every second is usually plenty to catch someone without lagging the game. Use events like Task.wait() effectively and try to use math that isn't too heavy on the CPU. Vector magnitude checks are generally pretty fast and reliable for distance-based security.
Keeping your library up to date
The "exploit scene" moves fast. New executors and scripts come out all the time. This means your security library shouldn't be a "set it and forget it" kind of thing. You should be looking at your server logs regularly. If you see a lot of weird activity or players complaining about a specific person, it's time to dive back into the code.
I've found that it's really helpful to build a "logging" feature into the library. Whenever the script catches something suspicious, it shouldn't just stop the action; it should log it to a private Discord channel or a spreadsheet. This way, you can see patterns. If you notice ten people all getting flagged for the same "speed" violation at the same spot in your map, it's probably a bug in your script, not an exploit.
Conclusion: Balancing fun and safety
At the end of the day, the goal of a roblox custom security library script is to make sure your players are having a good time. If your security is too strict, you'll end up kicking innocent people who just have bad ping. If it's too loose, the exploiters will run wild.
It takes some trial and error to find that sweet spot. Start small—maybe just protect your currency and your basic movement—and then expand as you see where the problems are. Building your own library might feel like a lot of work upfront, but it pays off when you can actually sleep at night knowing your game isn't going to be a hollowed-out shell of its former self by the time you wake up. Just keep it simple, keep it on the server, and always assume the client is trying to pull one over on you.