LSL syntax checker: check your Second Life script online

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What the checker finds

The checker reads your script the way the Second Life compiler does, without running it, and lists every problem with its line number and a tip in plain words:

• Syntax errors: a missing ; at the end of a line, a missing ) or }, an unclosed quote.
• Names: variables or functions that are used but never declared, typos and wrong capital letters (LSL is case sensitive), and names that clash with built-in LSL constants, such as SCALE or ROTATE.
• Types: a string put into an integer, wrong casts, a function that returns a value without a return type.
• Function calls: too few or too many parameters for a built-in function.
• Warnings: variables that are never used, = written where == was meant, conditions that are always true or false.
• Second Life traps: more than 12 llDialog buttons, button labels over 24 bytes, llDialog text over 512 bytes, hover text over 254 bytes, and a global key compared with NULL_KEY before it has a value.

How to use it

1. Copy your script from the viewer's script editor (Ctrl+A, then Ctrl+C).
2. Paste it into the box above and press Check script.
3. Click a result to jump to that line. Fix it, then check again until no errors are left.

Not sure where to start? Press Load an example to see a script with two small mistakes.

What it cannot check

The checker does not run your script, so it cannot know what happens in-world: whether an object has the right items in its Contents, whether permissions are granted, or whether the script runs out of memory while it works. A clean result means the script should compile; always test it in Second Life too.

Linden Lab adds new LSL functions from time to time. If a brand new function is reported as unknown, the checker's list may simply be one update behind.

About the checker

The checker uses lslint, a free and open-source LSL checker that many Second Life scripters use, with extra checks from WhatSL for common in-world traps. Your code is sent to our server only to be checked, and deleted right away. It is never stored or shared.

Looking for ready-made scripts? Browse our free LSL scripts.

Frequently asked questions

Is the LSL checker free?

Yes. You can check as many scripts as you like. There is only a short pause if very many checks come from the same place in a few minutes.

Does a clean result mean my script works?

It means the script should compile in Second Life. Whether it does what you want can only be tested in-world.

Is my script safe here?

Yes. Your script is checked and deleted right away. It is never stored, shown to anyone or used for anything else.