Free LaTeX checker
Paste a snippet or a full document and see whether it actually compiles.
What this checks
Your LaTeX is compiled with LuaLaTeX in a locked-down, ephemeral sandbox - no file or shell access, short timeout, nothing kept afterward. If you paste a bare snippet (like an equation), it's automatically wrapped in a minimal document so it can compile on its own; if you paste a full document with its own \documentclass, that's used as-is.
FAQ
Why does it reject some commands?
Since this tool compiles input from anyone on the internet, a small set of file- and shell-related commands (like \input, \write18, or \directlua) are blocked - normal math, chemistry (via mhchem), and text formatting are unaffected.
Can I check a whole paper?
Yes, up to 20,000 characters - past that, split it into sections and check each separately.