Mistral Medium 3.5: A Single 128B Open-Weight Model That Replaces Three Separate Models

One Model, Three Jobs

Mistral AI released Mistral Medium 3.5 on April 29, 2026 under a Modified MIT license. The model consolidates three previously separate Mistral offerings: Mistral Medium 3.1 for instruction-following, Magistral for reasoning, and Devstral 2 for coding. Users now switch between modes with a single toggle.

Specifications

Parameters: 128B (dense, not MoE)

Context window: 256K tokens

License: Modified MIT

SWE-bench Verified: 77.6%

API input price: $1.50 per million tokens

Self-hostable: On 4 GPUs

Ships with Vibe

Medium 3.5 launches alongside Vibe, a cloud-based coding agent that autonomously submits pull requests to GitHub. Together, they represent Mistral's push into agentic coding workflows.

Competitive Position

Among open-weight models, 77.6% on SWE-bench Verified is top-tier. The ability to self-host on four GPUs lowers the enterprise barrier significantly for teams with data residency constraints.

Source: Mistral AI, Winbuzzer