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Kimi K2 (0905) vs o3

2 vs 0 benchmarks won

Moonshot AI
Kimi K2 (0905)
OpenAI
o3
Overview
CompanyMoonshot AIOpenAI
Release dateSep 5 2025Apr 16 2025
Model type
Open sourceYesNo
Specifications
Parameters
1T
Context window
256k
Benchmarks
Science reasoning
GPQA Diamond
75.1%
Software engineering
SWE-Bench Verified
65.8%
Multimodal understanding
MMMU
Timeline
Release gapo3 shipped 142 days before Kimi K2 (0905)

Which is better: Kimi K2 (0905) or o3?

Kimi K2 (0905) leads o3 on 2 of the tracked benchmarks (GPQA Diamond, SWE-Bench Verified, MMMU). o3 shipped 142 days before Kimi K2 (0905), so benchmark comparisons should account for the intervening progress.

Kimi K2 (0905) is an open-source / open-weight model; o3 is proprietary.

Direct benchmark comparisons are unavailable — at least one of these models has not published scores on GPQA Diamond, SWE-Bench Verified, or MMMU.

Frequently asked questions

When was Kimi K2 (0905) released?
Kimi K2 (0905) was released by Moonshot AI on Sep 5 2025.
When was o3 released?
o3 was released by OpenAI on Apr 16 2025.
Is Kimi K2 (0905) or o3 open source?
Kimi K2 (0905) is an open-source / open-weight model released by Moonshot AI. o3 is a proprietary model released by OpenAI.

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