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Leanstral 1.5

Language Retired Full comparison ↗

mistral/leanstral-1-5 · by Mistral AI · mixture-of-experts

Retired

Retired on 2026-09-30. Its last published prices are below.

Pricing — 1 offering(s)

Mistral AI

About this offering: Retired. Mistral deprecated Leanstral 1.5 on 2026-09-29 and retired it on 2026-09-30, with no replacement listed. Leanstral 1.5 (Mistral AI, released 2026-06-30): a purpose-built model for Lean 4 formal proof engineering and automated theorem proving, not a variant of Mistral Large, Small or Codestral. Mixture-of-experts with 119B total parameters and about 6–6.5B active (Mistral's own sources differ), a 256K-token context, text in and out. Open weights under Apache-2.0. It's released under Mistral's Labs label (API id labs-leanstral-1-5), so treat it as experimental. The API is free for a limited period, with no end date announced (checked 2026-09-28).

Per-token usage

Retired — no longer sold · last price $0.00 / 1M tokens, until 2026-09-29

  • $0.00 / 1M tokens Historical 2026-06-30 → 2026-09-29
    Listed as "Price $0" on Mistral's own model-card pricing row — this is the model's own stated price, not a…

    Listed as "Price $0" on Mistral's own model-card pricing row — this is the model's own stated price, not a claim about the platform-wide rate-limited Experiment tier that applies to all Mistral models. The source page shows one flat price rather than separate input/output figures, so recorded here as unified per_1m_tokens rather than split input/output tiers. Free access under Mistral's "Labs" branding for an experimental research release. Mistral's own Labs policy page (docs.mistral.ai/models/labs) states Labs-tier models "may be deprecated or removed with 2 weeks' notice," are "experimental and fast moving models available for a limited amount of time," and that Mistral does "not recommend using these models in production environments." No scheduled future price is announced (unlike some Anthropic entries in this registry with an announced introductory-to-standard pricing window) — the real risk here is the model/endpoint being removed on short notice, not a price increase on a known date. Confirmed 2026-07-09.

Showing the active price and any recorded history. Full pricing history is available via the paid API — see API docs.

Citations