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DeepSeek: DeepSeek V4.1 Flash
deepseek/deepseek-v4.1-flashDeepSeek V4.1 Flash is a sparse mixture-of-experts model from DeepSeek, and the cost-efficient tier of the V4.1 family. DeepSeek reports that it exceeds V4 Pro on performance, speed, and task completion time, so it sits ahead of the previous flagship rather than beneath it.
It is suited for coding, reasoning, and agentic workflows, and is particularly strong at long-horizon tasks that must run to completion across many steps.
Modalities
Price in / out
Cache, read / write
Context / Max output
1.05M / 393K
Released
Sep 10, 2026
Additional rates
Flex, in / out
During some UTC hours the upstream charges 2× more — per-route rates are in the table below.
Parameters
messagesrequiredreasoning_effortoff · low · high · maxmax_tokensoptional · alias max_completion_tokensstreamtrue · falsetoolsfunction calling (OpenAI format)tool_choiceauto · none · requiredresponse_formatjson_object · json_schemaweb_search · · · providerrouting: order · only · ignore · sortservice_tierflex · prioritystream_options{"include_usage": true}image_urlimage (data: URL)Fine-tuning · 11
temperature0–2stopoptionalseedoptionaltop_p0–1top_koptionalmin_p0–1frequency_penalty−2…2presence_penalty−2…2repetition_penalty0–2logprobstrue · falsetop_logprobs0–20How to use via API
from openai import OpenAI
client = OpenAI(base_url="https://api.mixen.ai/v1", api_key="mxn-...")
resp = client.chat.completions.create(
model="deepseek/deepseek-v4.1-flash",
messages=[{"role": "user", "content": "Привет"}],
reasoning_effort="low", # off · low · high · max
temperature=0.7,
max_tokens=1024,
stream=False,
)
print(resp.choices[0].message.content)
# Стриминг: stream=True — ответ приходит чанками
for chunk in client.chat.completions.create(
model="deepseek/deepseek-v4.1-flash",
messages=[{"role": "user", "content": "Привет"}],
stream=True,
):
print(chunk.choices[0].delta.content or "", end="", flush=True)
# эконом-тир: тот же ответ вдвое дешевле, но ниже приоритет в очереди
cheap = client.chat.completions.create(
model="deepseek/deepseek-v4.1-flash",
messages=[{"role": "user", "content": "Привет"}],
extra_body={"service_tier": "flex"},
)
