Artificial intelligence coding startup, Cursor, faced backlash after revealing its latest Composer 2 model was built on Kimi K2.5, an open-source platform from China’s Moonshot AI.
Tipranks reported the controversy erupted on March 19, when developer Fynn scrutinized Composer 2s API calls, alleging it was essentially Kimi 2.5 with added reinforcement learning tweaks. This claim was supported by an internal identifier found in the system’s responses, leading to criticism on platforms such as Reddit and LinkedIn.
Cursor, which has a reported valuation of $29.3 billion, initially did not mention Moonshot AI in its announcement. Lee Robinson, Cursor’s vice president of Developer Education, later acknowledged the use of an open-source base model, stating that only a quarter of the compute relied on that foundation, with the rest stemming from proprietary training.
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