LuaJIT
Hacker ApprovedThe most recommended of 3 lua runtimes
Fast Lua 5.1 implementation with a JIT and easy C FFI, used in production for years. Critics say it is stuck on 5.1 and not fully PUC Lua compatible.
Fast Lua 5.1 implementation with a JIT and easy C FFI, used in production for years. Critics say it is stuck on 5.1 and not fully PUC Lua compatible.
69 people gave an opinion
- recommend it
- 51
- criticize it
- 18
- approval share
- 74%
Recommended in 12 of 13 months
- November 2025: recommended
- December 2025: recommended
- January 2026: recommended
- February 2026: recommended
- March 2026: recommended
- April 2026: recommended
- May 2026: recommended
- June 2026: recommended
- July 2026: recommended
- August 2026: recommended
- September 2026: recommended
- October 2026: recommended
- November 2026: not recommended (month in progress)
Why it carries the badge
- 51 people recommend itNeeds 10 or more, met.
- 2.8 recommenders for every criticNeeds 2 to 1 or better, met.
- Recommended in 12 of 13 monthsNeeds 4 or more, met.
The same three rules apply to every product, and the badge can’t be bought. How the badge works
What people say about it
The reasons people give, with the number of comments that give each one. Open a reason to read what they said.
Why people recommend it
Each mark is one comment
Very fast, near C performance
“LuaJIT is best in class performance for a scripting language -by a huge margin.”
Comment from 24 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS” “handles double, strings, and dictionaries at near C level performance”
Comment from 28 Oct 2026 in “Python's experimental JIT to be removed” “LuaJIT is still more performant and more widely used than PUC Lua”
Comment from 24 Dec 2025 in “Lua 5.5” - Comment from 23 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS”
- Comment from 14 Feb 2026 in “Vim 9.2 Released”
Easy C FFI integration
“Fortunately love is built on LuaJIT, which does support integer math through the built-in ffi library.”
Comment from 19 Apr 2026 in “It's OK to compare floating-points for equality” “it's a lot easier to write an API layer in Lua with LuaJIT than it is to do from C”
Comment from 25 Jun 2026 in “LuaJIT 3.0 proposed syntax extensions” “using luajit so that the lua runs very fast and has a super easy C FFI”
Comment from 5 Apr 2026 in “LÖVE: 2D Game Framework for Lua” - Comment from 24 Dec 2025 in “Fabrice Bellard Releases MicroQuickJS”
- Comment from 6 Apr 2026 in “LÖVE: 2D Game Framework for Lua”
Used in production for years
“wrote entire stacks and apps on top in LuaJIT that I got paid for and are running without any problems after many years”
Comment from 18 Oct 2026 in “Teal – A statically-typed dialect of Lua” “LuaJIT is still more performant and more widely used than PUC Lua”
Comment from 24 Dec 2025 in “Lua 5.5” “Luajit is already popular and has plenty of benchmarks online.”
Comment from 24 Nov 2025 in “Fast Lua runtime written in Rust” - Comment from 29 Aug 2026 in “Indirect Calling of Nested Functions on GCC Without Executable Stack”
Small, simple language core
“Keeps implementation much simpler and much faster, + it makes you be more careful how you are structuring and writing your code.”
Comment from 26 Jul 2026 in “Show HN: LuaJIT with Native SIMD” “I really liked the idea of the simplicity and size of Lua/luajit”
Comment from 28 May 2026 in “The Green Side of the Lua” “LuaJIT is king because Lua is such a small language”
Comment from 21 Apr 2026 in “How to Make a Fast Dynamic Language Interpreter”
What people warn about
Each mark is one comment
Diverges from PUC Lua
“Seems like a bad idea to actively diverge from Lua, hostile even, especially without at least a clear change of name.”
Comment from 25 Jun 2026 in “LuaJIT 3.0 proposed syntax extensions” “Why not work together with the PUC Lua team to add some of these to both lua versions”
Comment from 25 Jun 2026 in “LuaJIT 3.0 proposed syntax extensions” “I don't know why they are diverting from lua spec on other aspects though.”
Comment from 25 Jun 2026 in “LuaJIT 3.0 proposed syntax extensions” - Comment from 25 Jun 2026 in “LuaJIT 3.0 proposed syntax extensions”
Stuck on Lua 5.1
“From what I've heard it in practice isn't developed anymore and is stuck at Lua 5.1 still.”
Comment from 23 Dec 2025 in “Lua 5.5” “So is LuaJIT resuming active development after a decade or so of only maintenance? Great!”
Comment from 25 Jun 2026 in “LuaJIT 3.0 proposed syntax extensions” “LuaJIT has held back the lua ecosystem for over a decade”
Comment from 25 Jun 2026 in “LuaJIT 3.0 proposed syntax extensions” Syntax extensions add complexity
“It will make everything more complicated as there are now two ways to do everything.”
Comment from 25 Jun 2026 in “LuaJIT 3.0 proposed syntax extensions” “I dislike basically everything about these syntax extensions.”
Comment from 25 Jun 2026 in “LuaJIT 3.0 proposed syntax extensions” “This stuff (especially the ternary) are a step backwards.”
Comment from 25 Jun 2026 in “LuaJIT 3.0 proposed syntax extensions”
Other lua runtimes people recommend
The two most recommended other lua runtimes, with the same counts for each, so you can compare like for like. The tick on each bar marks the 2 to 1 line the badge needs.
See all 3 lua runtimes, rankedWhat people said
40 of the 84 comments that mention it, newest first. Each links to the original comment.
“handles double, strings, and dictionaries at near C level performance”
“wrote entire stacks and apps on top in LuaJIT that I got paid for and are running without any problems after many years”
“LuaJIT (which is comparable to or faster than V8 performance-wise”
“The most well known implementation is probably LuaJIT.”
“Keeps implementation much simpler and much faster, + it makes you be more careful how you are structuring and writing your code.”
“you can also get LuaJIT and SDL (2 or 3, probably should use 3) to work without it”
“it's a lot easier to write an API layer in Lua with LuaJIT than it is to do from C”
“Why not work together with the PUC Lua team to add some of these to both lua versions”
“I default to using LuaJIT, and have never had an issue with the actual code.”
“This stuff (especially the ternary) are a step backwards.”
“I don't know why they are diverting from lua spec on other aspects though.”
“LuaJIT has held back the lua ecosystem for over a decade”
“it will help with the adoption of the JIT, but the whole language could have been syntax modernized as a result”
“In aggregate this looks like a godsend, but there are some examples (like foo?.:method) that looks atrocious.”
“I dislike basically everything about these syntax extensions.”
“Seems like a bad idea to actively diverge from Lua, hostile even, especially without at least a clear change of name.”
“It will make everything more complicated as there are now two ways to do everything.”
“It's not fully compatible with PUC Lua (the reference implementation)”
“So is LuaJIT resuming active development after a decade or so of only maintenance? Great!”
“The language implementation that is faster than (!) C and almost as flexible as Lisp is called LuaJIT.”
“Luajit and SBCL are very much performance competitive with the JVM?”
“I really liked the idea of the simplicity and size of Lua/luajit”
“LuaJIT is a version of Lua 5.1 which is an incredibly fast scripting language”
“has plugins that improve the performance of strings and tables”
“LuaJIT is king because Lua is such a small language”
“Fortunately love is built on LuaJIT, which does support integer math through the built-in ffi library.”
“You don't even need to go all V8, you could just build something like LuaJIT and get most of the way there.”
“due to LuaJIT's great FFI you can just write whatever”
“Luajit is a whole other beast. I'd argue it's superior to anything in JS/JAVA/C# land”
“using luajit so that the lua runs very fast and has a super easy C FFI”
“it lets you create metaclasses around C objects, which is much easier than messing with the Lua stack from C”
“The JIT is also the real deal, with millisecond cold start execution delays”
“Lua, especially with LuaJIT, is nearly as fast as C.”
“LuaJIT is still more performant and more widely used than PUC Lua”
“LuaJIT is best in class performance for a scripting language -by a huge margin.”
“LuaJIT’s C FFI integration is super useful in a scripting language”
“From what I've heard it in practice isn't developed anymore and is stuck at Lua 5.1 still.”
“extremely high CPU performance for a scripting language”
“the compiler needs to do very little work and can hide the true cost of using something like Lua (LuaJIT)”
“Luajit is already popular and has plenty of benchmarks online.”
Counts come from 1,795,640 Hacker News comments, November 2025 to November 2026. How we count. Report a mistake.