Cursor's new Composer 2.0 is apparently based on Kimi2.5
Network traffic reveals Cursor's flagship AI feature is powered by Moonshot AI's Kimi 2.5 model.
A viral discovery by a developer on X has revealed that Cursor's newly launched Composer 2.0, its flagship AI-powered code editor feature, is not powered by an in-house model as many assumed. Network traffic analysis shows the tool sends requests to a model endpoint explicitly named `accounts/anysphere/models/kimi-k2p5-rl-0317-s515-fast`, directly linking it to Moonshot AI's Kimi 2.5 model. The finding, which was amplified by Elon Musk joining the conversation, suggests Cursor is leveraging a powerful, third-party Chinese LLM as the engine for its core AI functionality.
The situation highlights the common but often opaque practice in the AI tools space of building commercial products on top of existing foundation models. While the modified MIT license for Kimi likely permits this use, the lack of upfront disclosure by Cursor has sparked debate about transparency with users. For developers, the news clarifies the underlying capabilities of Composer 2.0, which is known for its strong reasoning and long-context handling—hallmarks of the Kimi model series. It also signals a competitive landscape where even Western-focused dev tools may integrate cutting-edge models from global AI labs.
- Network traffic exposes API call to `kimi-k2p5-rl-0317-s515-fast`, confirming Kimi 2.5 as the backbone.
- Elon Musk amplified the discovery, bringing major public attention to the model sourcing.
- Revelation questions transparency norms as companies build products on third-party models without explicit disclosure.
Why It Matters
Developers deserve to know what AI model powers their tools, as it directly impacts capabilities, privacy, and reliability.