Lua Decompiler

A decompiler, disassembler and deobfuscator for compiled Lua bytecode, written in Rust.

Try it online: lua-decompiler.com — runs entirely in your browser via WebAssembly; files are never uploaded.

Features

• Decompiles Lua 5.1, 5.2, 5.3, 5.4 and 5.5 bytecode (luac output) back to source: loops, if/elseif, and/or expressions, method calls, table constructors, closures, <close> variables, 5.5 named varargs (...t) and global declarations; local names come from debug info when present
• Decompiles Luau (Roblox) bytecode, versions 3–14, into valid Luau: continue, generalized iteration (for k, v in t), imports, table templates; opcodes scrambled by the Roblox client are recognised and decoded. Luau has no goto, so code that cannot be structured becomes a while loop over a state variable instead
• Decompiles LuaJIT 2.0 and 2.1 bytecode (luajit -b, string.dump), 32- and 64-bit: method calls, goto, table templates, FFI literals (1LL, 2ULL, 3i); bit operator instructions come back as bit.* calls
• Output is meant to behave exactly like the bytecode; unstructurable (irreducible) control flow falls back to goto
• Deobfuscation passes that only rewrite what they can prove equivalent: noise removal, opaque predicates and junk loops, constant folding and propagation, lookup-table resolution, string decoding (XOR ciphers and a bounded evaluator for decoder functions), constant/identity function inlining, dead-code removal, naming of re-bound API functions
• Control-flow unflattening for JMP-spaghetti obfuscators (5.1–5.3)
• Recovers Lua 5.2 files whose debug info was corrupted by obfuscators
• Bytecode disassembler, control-flow-graph export (Graphviz DOT) and an interactive bytecode debugger (5.1–5.3)

Decompilation is not perfect — if a file produces wrong output, please open an issue.

Command line

Requires Rust.

cargo build --release -p cli

# decompile
target/release/cli input.luac output.lua --decompile
# decompile + deobfuscate
target/release/cli input.luac output.lua --deobfuscate
# control-flow-flattened input (combine with --deobfuscate if needed)
target/release/cli input.luac output.lua --flatten
# bytecode listing
target/release/cli input.luac output.txt --disassemble
# control-flow graph of the main function
target/release/cli input.luac output.dot --dump-cfg

Interactive debugger (step through bytecode, inspect registers):

cargo run --release -p debugger --bin ldebug -- input.luac

Project layout

Crate	Purpose
disassembler	Bytecode model and listing (wraps luac-parser)
decompiler	CFG construction, structuring, AST generation, CFF linearization
lua_ast	Lua AST and pretty-printer
deobfuscator	AST-level deobfuscation passes
engine	Shared parse → decompile → deobfuscate pipeline
cli	Command-line tool
debugger	Interactive bytecode debugger (ldebug)
web	WebAssembly bindings and the lua-decompiler.com site — see web/README.md

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE)
• MIT license (LICENSE-MIT)

at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this work, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.