Lua Bytecode Viewer | luac Disassembler Online

Lua bytecode viewer for .luac files: lists every function, constant, string and instruction like luac -l. Reads Lua 5.1 to 5.5 in your browser. Free. Designed specifically for developers and professionals, this free online viewer runs entirely in your browser to process tasks quickly and securely. Enjoy unlimited usage with no data tracking and no registration required.

Also known as: lua bytecode viewer · luac disassembler online · view luac file online · lua bytecode decoder · luac -l online · lua 5.1 bytecode viewer · lua bytecode reader · luac file viewer · extract strings from lua bytecode

developer utilities

encoding and decoding tools

viewers

Bytecode Input

Drop a .luac or luac.out file here, or click to browse

Read locally with the File API. Nothing is uploaded.

Disassembly

The luac -l -l listing will appear here: every function with its instructions, constants, locals and upvalues

About Lua Bytecode Viewer

A Lua bytecode viewer is used to see what a compiled .luac file, or a loadstring() blob of bytecode inside a script, actually contains without running it. It parses the chunk in your browser and prints the same listing as luac -l -l: every function, its instructions with operands and source lines, and its constants, locals and upvalues, plus a searchable table of every string the code uses.

Key Features

Reads PUC Lua 5.1, 5.2, 5.3, 5.4 and 5.5 chunks, little- or big-endian, with 4- or 8-byte size_t
Prints the luac -l -l listing line for line, with labels F0, F1 and so on in place of memory addresses: opcodes, operands, jump targets, constants and upvalue names
Accepts a file, or pasted hex, base64, a {27,76,117,97,...} byte list or a Lua string with \27 and \x1b escapes
Lists every string constant with its function and index, filterable, so URLs, webhooks and keys stand out
Summarizes each function prototype: line range, parameters, varargs, upvalues, locals and instruction count
Works on stripped chunks too: line numbers show as [-] and the locals list is empty when luac -s removed the debug info

Use Cases

Inspect a suspicious loadstring() payload in a Roblox, Garry's Mod or FiveM script before you run it
Pull the strings out of a compiled World of Warcraft or LÖVE game file to find config keys and URLs
Check which Lua version a .luac file was compiled for when loading it fails with 'version mismatch'
Compare the bytecode two Lua versions generate for the same function while tuning hot code
Teach how the Lua VM works by showing real instructions next to the source lines that produced them

Supported Formats

.luac

luac.out

Lua 5.1 to 5.5 bytecode

hex

base64

byte list

Lua escaped string

Related Keywords

lua bytecode viewer

luac disassembler online

view luac file online

lua bytecode decoder

luac -l online

lua 5.1 bytecode viewer

lua bytecode reader

luac file viewer

extract strings from lua bytecode

Can this decompile Lua bytecode back to source?

No. This is a disassembler: it shows exactly what the compiled chunk holds, the instructions, constants, strings, function structure and, unless the file was stripped, line numbers and local names. A decompiler goes one step further and guesses Lua source from those instructions, which tools such as unluac and luadec attempt with mixed results. For most investigations the disassembly is enough, because every string, global name and function call is visible in it. Roblox Luau and LuaJIT use their own bytecode formats and are not supported.

Nothing leaves your browser

Files are read with the File API and pasted text is decoded in JavaScript. The bytecode is parsed, never executed, and nothing is uploaded. Only the pasted text and the text listing are kept in this tool's auto-save.

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Frequently asked questions

What is Lua Bytecode Viewer used for?

Lua bytecode viewer for .luac files: lists every function, constant, string and instruction like luac -l. Reads Lua 5.1 to 5.5 in your browser. Free.

Is Lua Bytecode Viewer free to use?

Yes. Lua Bytecode Viewer is completely free with no usage limits, and there is no paid tier required to use it.

Do I need an account to use Lua Bytecode Viewer?

No. Lua Bytecode Viewer works immediately in your browser with no signup, login, or email address required.

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