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Devstral 2 (123B) vs o1-preview

Mistral Devstral 2 (123B) vs OpenAI o1-preview — side-by-side specs.

Mistral
Devstral 2 (123B)
OpenAI
o1-preview
Overview
CompanyMistralOpenAI
Release dateDec 9 2025Sep 12 2024
Model type
Open sourceYesNo
Specifications
Parameters
Context window
Benchmarks
Science reasoning
GPQA Diamond
Software engineering
SWE-Bench Verified
Multimodal understanding
MMMU
Timeline
Release gapo1-preview shipped 453 days before Devstral 2 (123B)

Which is better: Devstral 2 (123B) or o1-preview?

Devstral 2 (123B) and o1-preview do not have directly comparable benchmark scores published on GPQA Diamond, SWE-Bench Verified, or MMMU. o1-preview shipped 453 days before Devstral 2 (123B), so benchmark comparisons should account for the intervening progress.

Devstral 2 (123B) is an open-source / open-weight model; o1-preview 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 Devstral 2 (123B) released?
Devstral 2 (123B) was released by Mistral on Dec 9 2025.
When was o1-preview released?
o1-preview was released by OpenAI on Sep 12 2024.
Is Devstral 2 (123B) or o1-preview open source?
Devstral 2 (123B) is an open-source / open-weight model released by Mistral. o1-preview is a proprietary model released by OpenAI.

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