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leanstral-1-5Mistral AI SAS

in /1Mfreeinput tokens
out /1Mfreeoutput tokens
context262K33K out
median ttft1.51smeasured
api
chat
hosting
EU
model lab
Mistral AI
weights
closed
added
May 2026
model id
mistral/leanstral-1-5

capabilities 2/8

visionreasoningtoolscachingweb searchjson schemacomputer useimage gen

pricing

no markup
input
free
output
free
cache write
-
cache read
-

worked cost

Estimated cost for three request volumes
volumecost
100K in + 10K outfree
1M in + 100K outfree
10M in + 1M outfree

Requesty charges what the upstream provider charges, with no markup and no per-request fee. Prompt caching and smart routing cut the effective cost further on repeated context. Gateway pricing

provider price, passed throughper 1M tokens

measured

through Sep 12
median ttft
1.51s
cache hit
61.1%

Weekly aggregates from production traffic routed through Requesty to this endpoint. A metric with no qualifying sample is left out rather than filled in. Compare against the other providers

benchmarks

artificial analysis
Benchmark scores, each normalised to 100
evalScore as a share of 100/100
MMLU Pro49.1
GPQA Diamond34.9
LiveCodeBench9.9
Intelligence Index5.5
Humanity's Last Exam3.5
5 evalsmean20.6

Scores from Artificial Analysis and public leaderboards, normalised to 100. Bar colour is the band, not the rank: green 80 and up, blue 55 and up, amber 30 and up. Benchmarks measure narrow skills, so test on your own workload before committing. Released 2023-12-11.

policy

data terms
retention
none
trains on prompts
no
hosted in
EU

Terms are the provider's, not Requesty's: routing a request here puts it under them. Mistral Privacy Policy

Need every request to stay in one jurisdiction? EU hosting routes only through EU-hosted providers.

quickstart

openai compatible
mistral/leanstral-1-5

this id pins the mistral ai sas deployment, with no routing and no failover. the managed id on the canonical page routes across all 1 providers instead

main.py
from openai import OpenAI client = OpenAI(    api_key="YOUR_REQUESTY_API_KEY",    base_url="https://router.requesty.ai/v1",) response = client.chat.completions.create(    model="mistral/leanstral-1-5",    messages=[        {"role": "user", "content": "Explain quantum computing in one paragraph."},    ],) print(response.choices[0].message.content)

Change the base url to https://router.requesty.ai/v1, use your Requesty key, set the model to the id above. Existing OpenAI SDK code needs no other edit, and the same key reaches every other model in the catalog. Browse all models

notes

reference

Leanstral 1.5 is an updated Lean 4 formal proof engineering model from Mistral AI, optimized for automated theorem proving and autoformalization. It has 119B total parameters with 6.5B active and supports a 256K token context window. It supports native function calling and structured output.

questions 6

How much does leanstral-1-5 cost?
leanstral-1-5 is priced at free per million input tokens and free per million output tokens when accessed via Requesty. Requesty charges exactly what the upstream provider charges, we don't add markup.
What is the context window of leanstral-1-5?
leanstral-1-5 has a context window of 262K tokens, with a maximum output of 33K tokens per response. That is roughly 350 words of input you can fit in a single prompt.
How does leanstral-1-5 perform on benchmarks?
leanstral-1-5 scores 49.1% on MMLU Pro, 34.9% on GPQA Diamond, 9.9% on LiveCodeBench. The benchmarks pane shows every published result, each normalised to 100.
What can leanstral-1-5 do?
leanstral-1-5 supports tool calling, structured outputs (JSON schema). You can call it through any OpenAI-compatible client by pointing base_url to Requesty.
How do I use leanstral-1-5 with the OpenAI SDK?
Install the OpenAI SDK, set base_url to "https://router.requesty.ai/v1", set your API key to your Requesty key, and set the model to "mistral/leanstral-1-5". The quickstart pane shows Python, JavaScript and cURL snippets.
Can I run leanstral-1-5 through Requesty?
Yes. leanstral-1-5 runs through Requesty's OpenAI-compatible API, served from Mistral AI SAS. You do not host the model yourself: point base_url at Requesty, set the model to "mistral/leanstral-1-5", and requests are routed to the upstream provider with automatic failover. The same key gives you 600+ other models too.

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call leanstral-1-5 through one endpoint

One key for this endpoint and 600+ other models. No markup on provider prices, automatic failover when a provider degrades, and prompt caching built in. Methodology

leanstral-1-5mistral ai sasin free /1Mout free /1Mctx 262Kttft 1.51shosted EU