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Devstral

Mistral · Devstral & Leanstral line · coding · open weights

Released May 21, 2025Replaced by Devstral 2

What changed

No verified summary yet. We only publish what the maker's own numbers support, so this card fills in as the sources come in.

Where the Devstral & Leanstral line stands

Leanstral 1.5 is the current model in this line. The card shows how long it has been since the last release against the line's usual gap and its recent ones — the rhythm, not a date.

Leanstral 1.5

Mistral · Devstral & Leanstral line · coding · open weights
Mid-cycle69 of ~108 days into its usual cycle

Apache 2.0 model for Lean 4 proof engineering with 119B parameters and 6B active, solving 587 of 672 PutnamBench problems.

Released Jul 2, 2026 · what changed →
Days since last release
Leanstral 1.5 · Jul 2, 2026
69
days
Usual gap
108
days
Recent gaps
Leanstral 1.5 · Jul 2026
108
Leanstral · Mar 2026
97
Devstral 2 · Dec 2025
202

Every Devstral & Leanstral release

Newest first. See the full line with every card →

  1. Jul 2, 2026Leanstral 1.5
  2. Mar 16, 2026Leanstral
  3. Dec 9, 2025Devstral 2
  4. May 21, 2025Devstral · this page

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