Luau was open-sourced under the MIT License in November 2021.
Luau is Roblox’s gradually typed scripting language, derived from Lua 5.1. Roblox developed it to serve the increasingly large and complex games built on its platform. It adds features such as optional type annotations, performance improvements, and sandboxing while retaining broad compatibility with Lua syntax.
Roblox first released Luau to platform developers in August 2019. On November 3, 2021, the company published the language’s runtime, compiler, type checker, and linter as open-source software. The MIT License allows people to use, modify, and redistribute the code with relatively few restrictions, making it notably more permissive than licenses such as the GPL.
A common mix-up is confusing Luau with Lua itself. Lua is the earlier programming language created at PUC-Rio in Brazil; Luau is Roblox’s independently developed dialect and tooling ecosystem. Luau remains the primary language used for scripting Roblox experiences, although it has also attracted interest from developers outside Roblox.