A roblox custom sanitization script is one of those things you don't realize you need until your game's data stores are a mess or your UI is breaking because someone decided to name their pet a string of 500 hashtags and weird symbols. While Roblox does a lot of the heavy lifting with their built-in TextService and chat filters, those tools are mainly there to keep things "all ages" and safe. They aren't necessarily built to keep your data clean or your UI looking professional. That's where writing your own custom layer comes in handy.
When we talk about sanitization in the context of Roblox, we aren't just talking about blocking "bad words." We're talking about stripping out invisible characters that mess up your layout, preventing players from injecting rich text tags where they shouldn't be, and ensuring that whatever a player types won't break your scripts later down the line. It's about taking raw, messy input and turning it into something predictable.
Why You Can't Just Rely on the Default Filter
Don't get me wrong—you have to use the Roblox filter. If you're displaying text from one player to another, the Terms of Service are pretty clear: run it through FilterStringAsync or risk getting your game (or account) moderated. But that filter is a "black box." You send it a string, and it sends back a version with hashtags.
The problem is that the standard filter doesn't care about your game's logic. If you have a system where players can name their house, and a player uses a bunch of weird Unicode symbols that look like vertical lines, the Roblox filter might see that as "safe." However, your UI might stretch into oblivion or look like it's glitching out. A roblox custom sanitization script allows you to define the rules for what fits your game's aesthetic and functional requirements.
Stripping Out the Junk
The core of any good sanitization script usually involves string manipulation. In Luau (Roblox's version of Lua), we have some pretty solid tools for this, specifically the string library and patterns. One of the most common things I find myself doing is stripping out "non-alphanumeric" characters.
If you're making a naming system, you probably don't want players using characters like \n (new lines) or \t (tabs). These can be used to "spoof" chat messages or push text way down off a sign. You can use string.gsub to find anything that isn't a letter or a number and just delete it. It's a bit aggressive, sure, but it's the safest way to ensure your data stays tidy.
Dealing with Rich Text Injection
Roblox recently made RichText a lot more accessible for UI elements. It's great for making bold words or colorful highlights, but it's a nightmare if you let players provide the input. Imagine a player names themselves Hacker. If your leaderboard has RichText enabled, their name is now going to show up in bright red, possibly confusing other players into thinking they have some special admin status.
Your roblox custom sanitization script should definitely have a pass for these types of tags. You can use patterns to look for < and > and either escape them or remove the content inside entirely. Most of the time, I just strip the brackets. It's easier and usually gets the job done without overcomplicating the logic.
White-listing vs. Black-listing
When you're setting up your script, you've got two main ways to go: you can either list everything you don't want (black-listing) or list only the things you do want (white-listing).
Honestly, white-listing is almost always the better way to go. If you try to black-list every weird symbol in the world, you're going to be at it forever. There are thousands of Unicode characters that can be used to bypass simple filters. If you instead say, "I only allow A-Z, 0-9, and basic punctuation," you've just closed the door on 99% of the nonsense people might try to pull.
It's a bit more restrictive for the player, but it makes your job as a developer a whole lot easier. You don't have to worry about the latest "glitch text" trend because your script just won't let it through the door.
Handling Data Store Integrity
Another reason you'd want a roblox custom sanitization script is for your DataStores. Roblox handles JSON encoding for you when you save tables, but if you're saving strings that contain weird control characters or massive amounts of data, you're just asking for trouble.
I've seen cases where players would try to paste entire scripts or massive "wall of text" emojis into a text box. If you save that directly to a DataStore, you might hit the character limit or, worse, end up with a corrupted entry that's hard to parse later. Sanitizing the length of the string is just as important as sanitizing the content. Always set a string.len limit. If they try to send 10,000 characters for a pet name that only needs 20, just cut it off at 20.
The "Silent" Sanitization Approach
One thing to consider is how you tell the player their input was "cleaned." You can be loud about it—show an error message saying "Invalid Characters Used!"—or you can be silent.
I usually prefer a mix. If a player types something clearly meant to be a name but adds a few weird symbols, I'll just strip the symbols and let the name go through. It's a smoother user experience. However, if the entire string is invalid, that's when you pop up the warning. You want the roblox custom sanitization script to feel like a helpful assistant, not a strict librarian who's constantly shushing the players.
Combining with the TextService
To wrap it all up into a functional system, your workflow should look something like this: 1. Capture the player's input from a TextBox. 2. Run your roblox custom sanitization script to remove prohibited characters, tags, and excess length. 3. Check if the string is still "meaningful" (i.e., not empty after cleaning). 4. Send that cleaned string to the server via a RemoteEvent. 5. On the server, run it through TextService:FilterStringAsync. 6. Finally, use the filtered result for display or storage.
Doing it in this order ensures that you aren't wasting your FilterStringAsync quota on absolute garbage, and it also ensures that the final product is both safe by Roblox's standards and clean by your game's standards.
Final Thoughts on Implementation
When you're actually writing the code, keep it modular. Don't bury your sanitization logic inside a 500-line "PlayerAdded" script. Put it in a ModuleScript in ReplicatedStorage. That way, you can use the same cleaning logic on both the client (for immediate feedback) and the server (for actual security).
Remember, you can't trust the client. Even if your client-side script cleans the text, a savvy player can bypass that and send a raw string to your RemoteEvent. You must run that roblox custom sanitization script on the server side before you do anything permanent with the data.
It might seem like a lot of extra work just to handle a few text boxes, but once you have a solid sanitization module in your toolkit, you can drop it into every project you make. It saves you from so many headaches regarding UI bugs, data corruption, and moderation issues down the road. It's just one of those "best practice" habits that separates the hobbyist devs from the pros. Plus, your players will appreciate a game that doesn't have "#####" or weird glitched text all over the leaderboards.