When was Mistral Medium 3.5 released?

Mistral Medium 3.5 was released by Mistral on Apr 29 2026.

When was Kimi K1.5 released?

Kimi K1.5 was released by Moonshot AI on Jan 20 2025.

How do the context windows of Mistral Medium 3.5 and Kimi K1.5 compare?

Mistral Medium 3.5 has a 256k context window; Kimi K1.5 has 128k.

Is Mistral Medium 3.5 or Kimi K1.5 open source?

Mistral Medium 3.5 is an open-source / open-weight model released by Mistral. Kimi K1.5 is a proprietary model released by Moonshot AI.

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Latest Release

Mistral Medium 3.5

Apr 29 2026

Home/Compare/Mistral Medium 3.5 vs Kimi K1.5

Mistral Medium 3.5 vs Kimi K1.5

1 vs 0 benchmarks won

	Mistral Mistral Medium 3.5	Moonshot AI Kimi K1.5
Overview
Company	Mistral	Moonshot AI
Release date	Apr 29 2026	Jan 20 2025
Model type	—	—
Open source	Yes	No
Specifications
Parameters	128B	—
Context window	256k	128k
Benchmarks
Science reasoning GPQA Diamond	—	—
Software engineering SWE-Bench Verified	77.6%	—
Multimodal understanding MMMU	—	—
Timeline
Release gap	Kimi K1.5 shipped 464 days before Mistral Medium 3.5

Which is better: Mistral Medium 3.5 or Kimi K1.5?

Mistral Medium 3.5 leads Kimi K1.5 on 1 of the tracked benchmarks (GPQA Diamond, SWE-Bench Verified, MMMU). Kimi K1.5 shipped 464 days before Mistral Medium 3.5, so benchmark comparisons should account for the intervening progress.

Context windows are 256k (Mistral Medium 3.5) vs 128k (Kimi K1.5). Mistral Medium 3.5 is an open-source / open-weight model; Kimi K1.5 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 Mistral Medium 3.5 released?: Mistral Medium 3.5 was released by Mistral on Apr 29 2026.
When was Kimi K1.5 released?: Kimi K1.5 was released by Moonshot AI on Jan 20 2025.
How do the context windows of Mistral Medium 3.5 and Kimi K1.5 compare?: Mistral Medium 3.5 has a 256k context window; Kimi K1.5 has 128k.
Is Mistral Medium 3.5 or Kimi K1.5 open source?: Mistral Medium 3.5 is an open-source / open-weight model released by Mistral. Kimi K1.5 is a proprietary model released by Moonshot AI.