What is it?
Run Lua lets you try Lua, the small scripting language used in Roblox, game mods, Neovim and many apps, right in your browser. Code runs on Fengari, a complete Lua 5.3 virtual machine, with print, io.write and io.read for input, and the string, table, math, utf8, os and coroutine libraries. A 10-second limit stops endless loops from freezing the page.
Who is it for?
Young game makers learning scripting, modders testing a function, Neovim users, and students comparing programming languages.
How to use it
- Type your program in Lua code (Ctrl + Enter runs it), or tap Try a sample.
- For io.read(), put one answer per line in Input (for io.read()). io.read("n") reads a number, io.read() a whole line.
- Press ▶ Run. The first time it loads Lua (about 220 KB).
- Read the Output; use Copy output, Download .lua or Clear output.
Worked example
local n = io.read("n")
for i = 1, n do io.write(i * i, " ") end
print()
Type 5 in the Input box and press Run: the output is “1 4 9 16 25”. Use local for variables inside functions: it is faster and avoids surprises. Your code runs in your browser and is not uploaded.
Errors and how to fix them
- “The program ended with an error (see the output)”: the error message from the language is in the Output box. Read its last line first: it names the problem and the line number.
- stopped after 10 seconds: is there an endless loop?: a while or repeat loop never ends. Check that its condition changes inside the loop.
- attempt to call a nil value (global '…'): the function does not exist here. Roblox functions such as game:GetService are not available; plain Lua works.
- attempt to perform arithmetic on a nil value: a variable was never set, often because the Input box had too few lines.
Open the tool: Run Lua
Still stuck?
Contact support. Tell us which tool or page you were using, what you tapped, what you saw, and your phone or computer and browser (for example: Android phone, Chrome). We reply by email.
Questions, or an error not listed here?
Tell us in the comments: what you were doing, the exact message you saw, and your device and browser. We read every comment and add new fixes to this article.