[0] https://chainthink.cn/zh-CN/news/113784276696010804 - may have originally been https://x.com/apples_jimmy/status/2034920082602864990
[1] https://pbs.twimg.com/media/HD2Ky9jW4AAAe0Y?format=jpg&name=...
"Is Kimi K2.5 open source?"
"Yes, Kimi K2.5 is an open source AI model. Developers and researchers can explore its architecture, build new solutions, and experiment openly. Model weights and code are publicly available on Hugging Face and the official GitHub repository."
Our only modification part is that, if the Software (or any derivative works thereof) is used for any of your commercial products or services that have more than 100 million monthly active users, or more than 20 million US dollars (or equivalent in other currencies) in monthly revenue, you shall prominently display "Kimi K2.5" on the user interface of such product or service.
But at least the rumor mill has them significantly above that line:
> Revenue: As of March 2026, reports suggest Cursor has surpassed $2 billion in annualized revenue (ARR).
It's definitely not what Kimi wanted, but it sounds like this is what is written.
You can't just add random terms to an existing license and use its name. "Modified MIT: Like MIT but pay us 50 million dollars."
Perhaps CC-BY would've been more appropriate.
“ CC-BY 4.0 Creative Commons Attribution 4.0 International
This license requires that reusers give credit to the creator. It allows reusers to distribute, remix, adapt, and build upon the material in any medium or format, even for commercial purposes.
BY Credit must be given to you, the creator. ”
it's annoying the open source term is being cargo-culted around and I hate to say it but that ship looks like it has sailed.
funny that free software people were infuriated by the open source term and now the open source term is being completely misused in another context
I had the question "how do you even enforce this weird license term" back then, I guess I know the answer now.
Before people go jumping to conclusions about model theft, it's worth considering the possibility that they did reach an agreement with Moonshot which their researchers were not aware of. That would certainly explain the deleted tweets. Until Moonshot makes an official statement, I'm not particularly concerned.
Their moat looks pretty thin. A VSCode fork with an open-source LLM fork on top. In the fast-moving coding-agent market, it’s not obvious they keep their massive valuation forever.
but it never occurred to me that, if true, of course the harness becomes increasingly more important. which feels absolutely correct of course.
not sure if the hypothesis is even true though.
Their value is in the data they've collected and are collecting. Usage, acceptance rate, and all the connected signals. Plus having a large userbase where they can A / B test any finetune they create.
People home about Teams sucking, but its market share is several times that of Slack because of distribution.
I guarantee that Microsoft has even more data.
Are there any open models that come close? Why doesnt OAI or Anthropic dedicate some resources to blowing Cursor's model out of the water? Cursor's completion model is a sticking point for a lot of users.
Equally as annoying, the break from VSCode is horrible. Having to use a separate registry, not having basic settings sync, the delay behind mainline VSCode updates.
Then, it's just plain buggier than others. The agent terminal just doesn't work semi-regularly, it doesn't like listing directories in the @, the SSH plugin crashes every other time it tries to connect, undoing agent work undoes edits I made in unrelated files sometimes. Sometimes updates just regress performance hard for seemingly no reason.
I also noticed the token use is wildly less efficient than CC or Codex these days. After almost no time at all it's up to 100,000 tokens and they're charging $1 per request for Sonnet. Side-by-side, Cursor spent $17 in the same time CC spent $4. Which is bizarre to me, since they advertise how their indexing and semantic search is more token efficient?
The autocomplete model was the only reason I stayed as long as I did. I wish there was a VSCode equivalent.
Which I find very unfortunate. There are so many cases, especially in proprietary codebases with non standard infrastructure, where good autocomplete is much better than "agentic" edits that produce nothing but slop which takes longer to clean up.
More to the point, beating Opus 4.6 at coding and coming within striking distance of gpt-5.4 is impressive! The benchmarks outperform raw Kimi K2.5.
It’s particularly impressive given larger labs like Meta are struggling to catch up to OpenAI/Anthropic.
https://www.bloomberg.com/news/articles/2026-03-12/ai-coding...
Would this have been extensively fine tuned, beyond what Anthropic/OAI would do themselves?
I guess this is Cursor's own benchmark, so you can finetune on your own dataset and get better results on your own specific tasks I guess.
> Our only modification part is that, if the Software (or any derivative works thereof) is used for any of your commercial products or services that have more than 100 million monthly active users, or more than 20 million US dollars (or equivalent in other currencies) in monthly revenue, you shall prominently display "Kimi K2.5" on the user interface of such product or service.
[1] - https://huggingface.co/moonshotai/Kimi-K2.5/blob/main/LICENS...
I'm also deeply curious about this legal question.
As I see it, model weights are the result of a mechanistic and lossy translation between training data and the final output weights. There is some human creativity involved, but that creativity is found exclusively in the model's code and training data, which are independently covered by copyright. Training is like a very expensive compilation process, and we have long-established that compiled artifacts are not distinct acts of creation.
In the case of a proprietary model like Kimi, copyright might survive based on 'special sauce' training like reinforcement learning – although that competes against the argument that pretraining on copyrighted data is 'fair use' transformation. However, I can't see a good argument that a model trained on a fully public domain dataset (with a genuinely open-source architecture) could support a copyright claim.
It goes against the ML community ethos to obscure it, but is common branding practice.
[0] https://chainthink.cn/zh-CN/news/113784276696010804
[1] https://pbs.twimg.com/media/HD2Ky9jW4AAAe0Y?format=jpg&name=...
I bet Moonshot is going to make them open their wallets to avoid legal trouble.
I think there's a reason why the people from Moonshot deleted their tweets; they're probably just researchers who got yelled at by the people who actually knew what was going on at Moonshot.
People need to seriously stop it with the whole reddit-esque Boston Marathon Bomber investigation-style low-info crusades. Its extremely unhealthy for both your own mental state and the state of discourse on the internet. Even if Cursor misbehaved (they did not): Your life is not materially changed whether they did or did not. Use it, or don't use it; these things are a matter that lies exclusively between Cursor and Moonshot.
There's just too many "features" the ux ends up being all over the place. I thought having the browser inside of the editor would be great for design, but it's not that much better than just having your browser open along with your editor.
They should have disclosed it though. If they didn't it's a bad look for sure.
Seems like cursor is trying to build a "thicker wrapper" beyond the harness. Either to protect against Anthropic shutting them off or increase margins.
This feels really rude to me. I have no problem with them fine-tuning open weight models to create their own - they are getting great results, and Cursor's research term should be respected for that. But deliberately hiding the base model they use is disrespectful of the researchers who created that model.
Currently I’ve not hit any of the limits despite using it quite rigorously, I wonder if this will change with a renewal?
I mean I guess this is what businesses do all the time. There's a term for it even, it's called white-labeling.
But is this all that Cursor have? They pass of VS Code as their own, they pass off Kimi as their own... What do Cursor even do? What do I need them for?
But can I rely on Cursor to be able to keep delivering, when they aren't the one's doing the work themselves?
What's way more likely is that Opus has been quantized by anthropic or something similar. Or that Opus was updated and didn't work well with Cursor's harness after. Or a token caching issue. Etc.
Why? As I said before, Anthropic mentions Moonshot AI (Maker of the Kimi models) as one of the AI labs that were part of this alleged "distillation attack" [0] campaign and will use that reason to cut off Cursor, Just like they did to OpenAI, xAI and OpenCode.
Let's see if the market thinks Composor 2 is really that good without the Claude models helping Cursor. (If Anthropic cuts them off).
[0] https://www.anthropic.com/news/detecting-and-preventing-dist...
The Anthropic ban on OpenCode isn't an Anthropic ban on OpenCode, it's a ban on using a Calude Code subscription with OpenCode. That's justified (or not) under various ToS arguments, but one can still use OpenCode with the more expensive API access.
Anthropic's complaint about distillation attacks is a distinct prong, one not levied against OpenCode. Additionally, the distillation activities described in your link don't describe Cursor's routine use of Anthropic's models. There, the model outputs are a primary product (e.g. the autocompleted code), and any learning signals provided are incidental.
Cursor is killed for this market.
I just downloaded VSCode again today after Cursor's latest update dropped my editor to 5 FPS or so (legitimately unusable. not hyperbole.) and holy shit it feels snappy. Completely forgot what it's like.
Ollama is also doing this.
There is so much money to be made repackaging open source these days.
So funny to see Twitter go wild saying "a 50 person team just beat Anthropic" blah blah.
The question is, where's the outrage? Why are there no headlines "USA steals Chinese tech?" "All USA can do is make a cheap copy of Chinese SOTA models".
> So funny to see Twitter go wild saying "a 50 person team just beat Anthropic" blah blah.
Well, if it's an American company, then it's a noble underdog story. When Chinese do it, they are thieves leeching on the US tech investment.
It's all so predictable, even the comments here.
[1] https://huggingface.co/moonshotai/Kimi-K2.5/blob/main/LICENS...
It's a bit more than that. They have plenty of data to inform any finetunes they make. I don't know how much of a moat it will turn out to be in practice, but it's something. There's a reason every big provider made their own coding harness.
Eg, When a prompt had a bad result and was edited, or had lots of back and forth to correct tool usage that information can be distilled and used to improve models.
And now imagine if you are focused on this for weeks you can likely come up with other ideas to leverage the metadata to improve model performance.
That said I have a feeling both VSCode and Claude code will catch up to their integration. But neither comes close yet (I say that as someone who mainly uses Claude Code).
I haven't dove into using a LLM in my editor, so I am less familiar with workflows there.
Cursor also has an interesting Debug mode that actively adds specific debug logging logic to your code, runs through several hypotheses in a loop to narrow down the cause, then cleans up the logging. It can be super useful.
Finally, when making peecise changes I can select a function, hit cmd-L and add certain ljnes of code to the context. Hard to do that in Claude. Cursor tends to be much faster for quicker, more precise work in general, and rarely goes "searching through the codebase" for things.
Most importantly, I'm cheap. a If I leave Cursor on Auto I can use it full time, 8 hours a day, and never go past the $20 monthly charge. Yes, it is probably just using free models but they are quite decent now, quick and great for inline work.
Cursor's auto mode is flaky because you don't know which model they're routing you to, and it could be a smaller, worse model.
It's hard to see why paying a middleman for access to models would be cheaper than going directly to the model providers. I was a heavy Cursor user, and I've completely switched to Codex CLI or Claude Code. I don't have to deal with an older, potentially buggier version of VS Code, and I also have the option of not using VS Code at all.
One nice thing about Cursor is its code and documentation embedding. I don't know how much code embedding really helps, but documentation embedding is useful.
[1] https://marketplace.visualstudio.com/items?itemName=ezforo.c...
How does this blow that narrative up? A 50 person team likely broke a license to have a product that's competitive on output at a fraction of the costs of one of the most well capitalized companies on the planet. Claude code and anthropic are certainly the darlings of the space today, but to me this just reinforces the idea that their moat is razor thin on the model front, even compared to OSS that can be run on independent hardware.
The application layer play is also suspect to me. In the medium to long term I _want_ tools that'll let me run whatever models I want vs being tied to an expensive, proprietary, and singular provider. For personal work I care about costs, and eventually my employer will care both about costs _and_ enterprise features/governance that a company like Anysphere is extremely well positioned to provide.
More and more, I see the future of the application layer being model agnostic, most enterprises hosting models on their own cloud for data security concerns, and the models being fully commoditized.
I would also not rule out that since K2 is an 1T model, this is a distill, as I don't think they're serving expensive models just like that, which would not be a licensing violation?.
These days? Almost every tech offering in existence is 1000+ OSS dependencies gaffer taped together with a sprinkling of business logic.
Cursor isn't a shocking bit of software to pay for, its investment however...
We know Composer 2 is Kimi K2.5 from that tweet. Where is the evidence for Composer 1 being based on Qwen?
> So funny to see Twitter go wild saying "a 50 person team just beat Anthropic" blah blah.
In this case, it will be the other way round: Anthropic will see Cursor as a competitor AI lab using open weight models for Composor 2 (actually Kimi K2.5) which was allegedly distilled from Opus 4.6, and would be enough for Anthropic to cut off Cursor from using any of models.
That's where it is going.