AI Model Release Tracker - Timeline of Major AI Models from 2022-2026

Mistral Medium 3.5 vs Grok 4 Heavy

Mistral
Mistral Medium 3.5
SpaceXAI
Grok 4 Heavy
Overview
CompanyMistralSpaceXAI
Release dateApr 29 2026Jul 9 2025
AccessOpen WeightProprietary
Specifications
Parameters
128B
Context window
256k
Benchmarks
Coding
SWE-Bench Verified
77.6%
Timeline
Release gapGrok 4 Heavy shipped 294 days before Mistral Medium 3.5

Which is better: Mistral Medium 3.5 or Grok 4 Heavy?

Mistral Medium 3.5 and Grok 4 Heavy don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Grok 4 Heavy shipped 294 days before Mistral Medium 3.5, so benchmark comparisons should account for the intervening progress.

Mistral Medium 3.5 is open weight, while Grok 4 Heavy is proprietary.

Direct benchmark comparisons are unavailable — Mistral Medium 3.5 and Grok 4 Heavy don't publish scores on any of the same benchmarks.

Frequently asked questions

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

Grok 4 Heavy was released by SpaceXAI on Jul 9 2025.

Mistral Medium 3.5 is an open weight model released by Mistral. Grok 4 Heavy is a proprietary model released by SpaceXAI.

Other comparisons