Kimi K2.5vsComposer 1.5
Kimi K2.5 | Composer 1.5 | |
|---|---|---|
| Specifications | ||
Parameters | 1T | — |
Context window | 256k | — |
| Benchmarks | ||
Nonsense detection BullshitBench v2Given a confidently-worded but nonsensical prompt, does the AI spot that it makes no sense and push back — instead of playing along and inventing an answer? The score is how often it clearly called out the nonsense. Higher is better. | 52% | — |
Coding SWE-Bench VerifiedReal coding tasks pulled from open-source projects — the AI has to find and fix actual bugs. A human-checked version of the original SWE-Bench. Higher is better. | 76.8% | — |
Agentic coding CursorBench v3.1Cursor's own test of harder, real-world coding tasks inside a code editor. Higher is better. | 31.9% | — |
Next.js coding Next.js EvalsVercel's open eval of how well AI coding agents build and migrate real Next.js apps — measured as the share of tasks the agent completes successfully. Higher is better. | 21% | 67%Best |
Competitive coding LiveCodeBenchCoding problems published so recently the AI can't have seen them in training — a contamination-free test of raw programming skill. Higher is better. | 85% | — |
Science GPQA DiamondGraduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | 87.6% | — |
Community preference (code) Arena Elo (Code)Like the text arena, but people vote on which AI writes better code. The votes become a chess-style Elo rating on arena.ai. Higher is better. | 1433 | — |
| Overview | ||
| Company | Moonshot AI | SpaceXAI |
| Release date | Jan 27 2026 | Feb 9 2026 |
| Access | Open Weight | Proprietary |
Which is better: Kimi K2.5 or Composer 1.5?
Composer 1.5 leads Kimi K2.5 on 1 of the 1 benchmark they both report (Next.js Evals). Kimi K2.5 shipped 13 days before Composer 1.5, so benchmark comparisons should account for the intervening progress.
Kimi K2.5 is open weight, while Composer 1.5 is proprietary.
On Next.js Evals, Composer 1.5 leads at 67% vs Kimi K2.5 at 21%.
Frequently asked questions
Kimi K2.5 was released by Moonshot AI on Jan 27 2026.
Composer 1.5 was released by SpaceXAI on Feb 9 2026.
Composer 1.5 leads on Next.js Evals — Kimi K2.5 21% vs Composer 1.5 67%.
Kimi K2.5 is an open weight model released by Moonshot AI. Composer 1.5 is a proprietary model released by SpaceXAI.
Other comparisons
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