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Composer 1.5 vs Devstral 2 (123B)

Cursor Composer 1.5 vs Mistral Devstral 2 (123B) — side-by-side specs.

Cursor
Composer 1.5
Mistral
Devstral 2 (123B)
Overview
CompanyCursorMistral
Release dateFeb 8 2026Dec 9 2025
Model type
Open sourceNoYes
Specifications
Parameters
Context window
Benchmarks
Science reasoning
GPQA Diamond
Software engineering
SWE-Bench Verified
Multimodal understanding
MMMU
Timeline
Release gapDevstral 2 (123B) shipped 61 days before Composer 1.5

Which is better: Composer 1.5 or Devstral 2 (123B)?

Composer 1.5 and Devstral 2 (123B) do not have directly comparable benchmark scores published on GPQA Diamond, SWE-Bench Verified, or MMMU. Devstral 2 (123B) shipped 61 days before Composer 1.5, so benchmark comparisons should account for the intervening progress.

Devstral 2 (123B) is an open-source / open-weight model; Composer 1.5 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 Composer 1.5 released?
Composer 1.5 was released by Cursor on Feb 8 2026.
When was Devstral 2 (123B) released?
Devstral 2 (123B) was released by Mistral on Dec 9 2025.
Is Composer 1.5 or Devstral 2 (123B) open source?
Devstral 2 (123B) is an open-source / open-weight model released by Mistral. Composer 1.5 is a proprietary model released by Cursor.

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