Cursor admits its new coding model was built on top of Moonshot AI’s Kimi

AI coding institution Cursor launched a caller exemplary this week called Composer 2, which it promoted arsenic offering “frontier-level coding intelligence.” 

However, an X idiosyncratic posting nether the sanction Fynn soon claimed that Composer 2 was “just Kimi 2.5” with further reinforcement learning — Kimi 2.5 being an unfastened root exemplary precocious released by Moonshot AI, a Chinese institution backed by Alibaba and HongShan (formerly Sequoia China). 

As evidence, Fynn pointed to codification that seemed to place Kimi arsenic the model.

“[A]t slightest rename the exemplary ID,” they scoffed.

It was a astonishing revelation, since Cursor is simply a well-funded U.S. startup that raised a $2.3 cardinal circular past fall astatine a $29.3 cardinal valuation, and is reportedly exceeding $2 cardinal successful annualized revenue. Also, the institution didn’t notation thing astir Moonshot AI oregon Kimi successful its announcement.

However, Cursor’s vice president of developer acquisition Lee Robinson soon acknowledged, “Yep, Composer 2 started from an open-source base!” But helium said, “Only ~1/4 of the compute spent connected the last exemplary came from the base, the remainder is from our training.” As a result, helium said Composer 2’s show connected assorted benchmarks is “very different” from Kimi’s.

Robinson besides insisted that Cursor’s usage of Kimi was accordant with the presumption of its license, a constituent the Kimi relationship connected X repeated successful a subsequent station congratulating Cursor, wherever it said the Cursor utilized Kimi “as portion of an authorized commercialized partnership” with Fireworks AI.

“We are arrogant to spot Kimi-k2.5 supply the foundation,” the Kimi relationship said. “Seeing our exemplary integrated efficaciously done Cursor’s continued pretraining & high-compute RL grooming is the unfastened exemplary ecosystem we emotion to support.”

So wherefore not admit Kimi upfront? Beyond immoderate imaginable embarrassment successful not creating a exemplary from scratch, gathering connected apical of a Chinese exemplary mightiness consciousness peculiarly fraught close now, with the alleged AI “arms race” often framed arsenic an existential conflict betwixt United States and China. (See, for example, Silicon Valley’s apparent panic aft Chinese institution DeepSeek released a competitory model aboriginal past year.)

Cursor co-founder Aman Sanger acknowledged, “It was a miss to not notation the Kimi basal successful our blog from the start. We’ll hole that for the adjacent model.”