Mojo is now open source

https://www.modular.com/blog/mojo-open-source

179•visheshdembla•1d ago

Comments

Lichtso•1d ago

Technically soruce available now with the promise of accepting contributions (thus becoming fully open source) early next year. But since it is an Apache 2 license (like the rest of the LLVM project) you are already allowed to fork and contribute to your own fork right now, just no upstreaming.

For many the closed source nature of the compiler was a knock-out criterion. We will see if Mojo can gain traction now or if it has missed its window of opportunity.

fluffybucktsnek•1d ago

Technically, the criteria for open source is freedom to freely distribute and modify the source code, not to upstream changes. That's a different for thing.

https://opensource.org/osd

cube2222•1d ago

It’s open source under the Apache 2 license, not source available.

Accepting contributions is not required to be open source.

SQLite doesn’t accept contributions from random people either [0] (though you could argue being public domain isn’t being open source).

Anyway, this is great, I was waiting for this to take the language for a spin! Congrats to the Mojo team!

[0]: https://simonwillison.net/2025/Dec/29/copyright-release/

roundabout-host•1d ago

Maybe it is not listed by the OSI, but it is 'open source' in practice, if the source is also in the public domain. The FSF's definition of free software makes more sense not only ideologically, but also because it does not try to be exhaustive.

SwellJoe•1d ago

You're just making up your own definitions of things.

If the complete source is available and distributable under an OSI-approved license, it is absolutely Open Source. Accepting outside contributions is nowhere in the definition of Open Source.

totalperspectiv•1d ago

This is really exciting. I've been using Mojo off and on for side projects over the last two years.

(copying from some previous Mojo threads) It's got an ownership system adjacent to Rust, comptime similar to Zig, and a first class dependent type system. Even more exciting, is that uses LLVM (to the best of my understanding) in some novel ways and for more optimizations.

dlahoda•1d ago

Hm, in docs they say that dependent type system is not first class seems.

Is it even dependent? More like refinement types, which seems will be in Rust too.Also HN recently mentioned Rust building similar llvm based integration with GPU.

But compared with Python, Julia, Matlab, R, Rust, C, C++ - Mojo feel relief for working with numerics.

Archit3ch•1d ago

> But compared with Python, Julia, Matlab, R, Rust, C, C++ - Mojo feel relief for working with numerics.

Out of those, Julia is the only one that combines Multiple Dispatch and native code, both important for numerics.

jondea•1d ago

I don't agree at all with your last paragraph. MATLAB and Julia are lovely for numerics, maths is terse and looks like maths! Mojo is hobbled by choosing Python style syntax, which does not lend itself well to maths.

WRT the type system, I agree MATLAB is a mess but Julia's multiple dispatch feels more like maths than any other language I've tried.

melodyogonna•1d ago

Related post with relevant pr: https://news.ycombinator.com/item?id=49347777

ChrisArchitect•1d ago

Mojo 1.0

https://news.ycombinator.com/item?id=49261128

melodyogonna•1d ago

Such an exciting time for Mojo, I don't think people realize just yet the innovation being brought to fore here.

vovavili•1d ago

The innovative potential of Mojo would be constrained to relatively niche and senior dev circles until they get a Windows release, which probably won't happen anytime soon. Python keeps the throne for now.

dloss•1d ago

They announced a partnership with Microsoft today.

vovavili•1d ago

That's quite promising - https://www.modular.com/blog/modcon-announcements#:~:text=Wi...

pjmlp•1d ago

And Julia as well.

rirze•1d ago

It's a sad time to be a fan of Julia-- everyone forgets it's there.

archargelod•

setopt•1d ago

Very exciting. Closed source was one of the main things making me not try it out yet.

Any good resources for getting started? And anything on doing NumPy/SciPy-like stuff in it?

MohamedMabrouk•1d ago

NuMojo is the closest thing in the ecosystem to numpy and the final aim is offer numpy-like experience. https://github.com/Mojo-Numerics-and-Algorithms-group/NuMojo

vovavili•1d ago

Can't you just use Numpy directly in Mojo?

MohamedMabrouk•1d ago

you can but through a python interpreter in the mojo process so you get the same numpy speed with mojo<->ptyhon interop overhead. NuMojo is native and also is now starting to support features that numpy can't really do like native GPU execution.

vovavili•1d ago

I wonder if the Python-to-Mojo overhead is significant enough where language-native bindings make more sense. I'd be interested in seeing some benchmarks.

totalperspectiv•1d ago

https://mojolang.org is the best spot for getting started generally. numojo is the closest thing to numpy right now. You can check out more packages here: https://github.com/modular/modular-community/tree/main/recip...

mrbonner•1d ago

So I think the permissive license like Apache 2 without opening up for upstream contributions would be the way of future open source development. In a very similar way of SQLite. It definitely will help shield off a bunch of AI generated contributions first and foremost and then, aligning mental model with the human contributions with Mojo leader team.

SwellJoe•1d ago

As long as it was proprietary, I could ignore it. Now, I guess I have to learn a little something about it.

ModernMech•1d ago

"Modular Confidential (obviously), May 14, 2022"

lol, feels like espionage

https://github.com/modular/modular/blob/main/KGEN/docs/Desig...

Compiler walkthrough

https://github.com/modular/modular/blob/main/KGEN/docs/MojoC...

melodyogonna•1d ago

One of my favourite features of Mojo is linear types and how deeply they have been integrated into manual memory management - see:https://x.com/melodyogonna/status/2085089269484343725?s=20. When I first learned about linear types, my first thought of the use case was making manual allocations and deallocations safer without sacrificing usability, but I didn't know what that could look like; now I do. This is great because in Mojo, pointers are surfaced a lot more than in, say, Rust, but such sharp tooling in a language you expect to be safe by default can be problematic. Linear types, combined with the origin system, give the language a lot of flexibility; it is like using a sharp tool with a safety glove: the tool isn't any less sharp, but the chances of accidentally injuring yourself are reduced.

branko_d•1d ago

Is this a case of of Qualcomm commoditizing their complements? Does Mojo have a potential for disrupting Nvidia's current market position?

https://www.joelonsoftware.com/2002/06/12/strategy-letter-v/

andsoitis•1d ago

Love this intentionality: ” Our open source approach has been deliberate: we’ve found that small and tight-knit design teams (not committees) are the best for finding the “soul” of a language, but that feedback from a broader community is essential to escape an echo chamber. As such, we first open-sourced the Mojo standard library, then released hundreds of thousands of lines of kernel code written in Mojo, tools, and support. We built together with community feedback and public design proposals, and are now open sourcing the compiler. We will continue to open our processes further as Mojo keeps maturing.”

dang•24m ago

Recent and related:

Mojo 1.0 - https://news.ycombinator.com/item?id=49261128 - Aug 2026 (244 comments)

WalterGR•16m ago

From yesterday:

The Mojo language (by Modular, now Qualcomm) is now open-source - https://news.ycombinator.com/item?id=49358327 - 108 comments

pmkary•5m ago

What a beautiful standard library btw. Much to learn and take from.

Alien1Being•4m ago

"Qualcomm to Acquire Modular 06/24/2026"

https://investor.qualcomm.com/news-events/press-releases/new...

Can acqui-death be far away...?

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