If you're tired of seeing messy text or potential vulnerabilities in your game, building a roblox custom sanitization script is probably high on your priority list. It's one of those things that sounds a bit boring until you realize how much it actually does to keep your game running smoothly and looking professional. Most people just think about the built-in Roblox chat filter, but there's a whole world of data cleaning that happens behind the scenes. Whether you're handling pet names, shop item descriptions, or even just custom UI inputs, you need a way to make sure what players type doesn't break your layout—or worse, your game logic.
Why You Actually Need One
You might be wondering why you can't just rely on Roblox's default systems. Well, you have to use TextService for actual filtering (that's the law of the land on Roblox), but filtering isn't the same thing as sanitization. Filtering hides the bad words; sanitization cleans up the structure of the string.
Think about it this way: a player could name their pet something totally "clean" according to the filter, but they might use 500 line breaks or a weird string of Unicode characters that stretches your UI across the entire screen. A roblox custom sanitization script helps you strip out those annoying characters, limit the length of the text properly, and ensure that the final result actually fits where it's supposed to go.
It's also about security. While Luau (Roblox's version of Lua) is pretty secure, you still don't want people trying to inject weird formatting or rich text tags where they don't belong. If your game uses RichText on labels, a player could potentially input a closing tag like </font> and mess up the rest of your UI's styling. A good script catches that before it happens.
The Difference Between Filtering and Sanitizing
It's easy to get these two mixed up, but they serve different masters. Filtering is about safety and compliance. Roblox requires you to run any text that players see through their FilterStringAsync methods. If you don't do this, your game might get flagged or even taken down.
Sanitizing, on the other hand, is about data integrity. It's where you decide that a "Player House Name" shouldn't have emojis, or that a "Trade Note" shouldn't exceed 100 characters. You're essentially scrubbing the input to make sure it follows your game's specific rules.
I usually recommend doing the sanitization first to get the string into the format you want, and then passing that cleaned-up string through the Roblox filter. This way, you aren't wasting the filter's "effort" on text that you were going to throw away anyway.
Getting Hands-on with String Manipulation
To build a roblox custom sanitization script, you're going to get very familiar with the string library. Specifically, string.gsub is going to be your best friend. This function allows you to search for patterns and replace them with something else—or nothing at all.
Using gsub Like a Pro
Let's say you want to get rid of every character that isn't a letter, a number, or a space. You can use a pattern like [^%w%s]. In Luau pattern speak, %w represents all alphanumeric characters, and %s represents whitespace. The ^ at the start of the brackets means "everything except these."
So, a simple line like input = string.gsub(input, "[^%w%s]", "") would effectively strip out symbols, emojis, and weird punctuation. It's a bit aggressive, but for something like a username or a high-score name, it works wonders.
Dealing with Whitespace
Another common headache is the player who hits the spacebar twenty times. It looks awful in your logs and even worse on a leaderboard. You can fix this by looking for multiple spaces and collapsing them into one. A pattern like %s+ finds one or more whitespace characters. You can replace that with a single space, and suddenly, the text looks like a human wrote it again.
Handling Multi-line Inputs and Newlines
If you're using a TextBox for longer inputs, players will inevitably try to spam the Enter key. If your UI isn't built for vertical scrolling, this will break your design.
A good roblox custom sanitization script should handle \n (newlines) and \r (carriage returns). You can either replace them with a space or just delete them entirely. If you do want to allow some newlines but not too many, you can write a little loop that counts how many times \n appears and trims the string if it exceeds your limit.
It's these little quality-of-life touches that make a game feel "polished" rather than "made in a weekend."
The Rich Text Trap
Rich text is a cool feature in Roblox, but it's a double-edged sword. If you have RichText enabled on a TextLabel, Roblox will interpret things inside <> brackets as formatting commands.
If a player types <b>Hello</b>, and you display that in a label with rich text enabled, it'll show up bold. That's fine, right? But what if they type <font size="100">BIG</font>? Now your UI is ruined.
To prevent this, you need to "escape" those characters. Basically, you turn < into < and > into >. Your roblox custom sanitization script can do this automatically. It's a vital step if you're making something like a custom chat or a billboard system where players have a bit more freedom with their words.
Performance and Optimization
You might be tempted to run your sanitization script every single time a player presses a key. While Luau is fast, doing complex string matching on the Changed event of a TextBox for every single player can add up, especially if your patterns are complicated.
It's usually better to sanitize the input in two stages: 1. On the Client: Give the player immediate feedback. If they type an illegal character, just remove it from the TextBox.Text immediately. This makes the game feel responsive. 2. On the Server: Never trust the client. Even if you have a perfect script on the local side, an exploiter can bypass it and send a raw string to your RemoteEvents. You must run your roblox custom sanitization script again on the server before you save the data to a DataStore or display it to other players.
Where to Put the Script?
Organization matters. I usually keep my sanitization logic in a ModuleScript inside ReplicatedStorage. That way, both the server and the client can access the same rules. You don't want the client thinking a name is valid while the server thinks it's invalid—that leads to those annoying bugs where a player clicks "Submit" and nothing happens, and they have no idea why.
By centralizing the logic, you can update your "banned character" list or your length limits in one place, and it'll update everywhere in your game instantly.
Wrapping Things Up
At the end of the day, a roblox custom sanitization script is about control. It's about making sure that the data flowing through your game is predictable. When your data is predictable, your UI doesn't break, your DataStores don't get cluttered with junk, and your players have a more consistent experience.
It's not the most glamorous part of game development, but once you have a solid sanitization module in your toolkit, you'll find yourself dropping it into every project you start. It saves so much time in the long run because you aren't constantly fixing "weird UI bugs" that turn out to be someone just typing 200 underscores in a row. Take the time to build a robust one, and your future self will definitely thank you.