How much does the DeepSeek V4.1 Flash API cost?

On FastMetal, DeepSeek V4.1 Flash is billed per token in yen: ¥50.69 per 1M input tokens and ¥202.74 per 1M output tokens, before tax. Usage is drawn from a prepaid balance; there is no subscription or monthly fee.

Can I call DeepSeek V4.1 Flash with the OpenAI SDK?

Yes. Point base_url at https://api.fastmetal.ai/v1 and pass "deepseek-v4.1-flash" as the model; existing OpenAI-style code works unchanged, including streaming, tool calls and structured output.

What is the context window of DeepSeek V4.1 Flash?

1,048,576 tokens, shared between the prompt and the response.

What do I need to try DeepSeek V4.1 Flash?

Create an account and add credit; the model is then available both in the browser chat and over the API. There is no contract or minimum spend.

Back to Models

deepseek/deepseek-v4-1-flash

DeepSeek V4.1 Flash

DeepSeek V4.1 Flash is a sparse mixture-of-experts model from DeepSeek, and the first built on the company's Causal Encoder-Decoder (CED) architecture. It activates 8B parameters on input and 16B on...

9/10/2026

1,048,576 tokens

Input: ¥50.686/M

Output: ¥202.7441/M

Try in Chat Get API Key

Specifications

Modalities

Input

text

image

Output

text

Supported Parameters

frequency_penalty

include_reasoning

logit_bias

logprobs

max_tokens

min_p

presence_penalty

reasoning

reasoning_effort

repetition_penalty

response_format

seed

stop

structured_outputs

temperature

tool_choice

tools

top_k

top_logprobs

top_p

Max Output Tokens

384,000

Reasoning Configuration

Default: Thinking on (effort: high)
Selectable effort levels: max
high
low
Turning thinking off: Possible (reasoning.enabled: false)

How to control thinking, and what it costs

Code Examples

curl https://api.fastmetal.ai/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "deepseek-v4.1-flash",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

How DeepSeek V4.1 Flash actually answers

Real responses to our standard prompts, recorded on FastMetal.

Count the number of 'r's in 'strawberry'

Count the number of 'r's in 'strawberry'. Explain your reasoning step by step.

The word **“strawberry”** has **3** letter **“r”**s. Step-by-step: 1. Spell it out: **s t r a w b e r r y** 2. Find each **r**: - Position 3: **r** in “str” - Position 8: first **r** in “berry” - Position 9: second **r** in “berry” 3. Total: **3** **Answer: 3**

7.5s response226 output tokens

Debug This Error

I'm getting the following error in my Node.js application: TypeError: Cannot read properties of undefined (reading 'map') at UserList (/app/components/UserList.js:12:25) at renderWithHooks (/app/node_modules/rea…

The error means that `users` is `undefined` when `UserList` renders, so JavaScript cannot call `.map()` on it. Your component expects a `users` prop: ```jsx function UserList({ users }) { return ( <ul> {users.map(user => <li key={user.id}>{user.name}</li>)} </ul> ); } ``` But it is being rendered without `users`, or `users` has not loaded yet. Common causes: 1. Parent renders it without the prop: ```jsx <UserList /> ``` instead of: ```jsx <UserList users={users} /> ``` 2. The prop name is different: ```jsx <UserList userList={users} /> ``` 3. The data is fetched asynchronously and is initially `undefined`: ```jsx const [users, setUsers] = useState(); useEffect(…

16.0s response945 output tokens

Code Review

Please review the following Python function and suggest improvements for readability, performance, and best practices: def get_data(url, retries=3): import requests import time for i in range(retries):…

Here are the main improvements: - Move imports to module level. - Avoid bare `except`; catch specific exceptions. - Use a `requests.Session` for connection reuse. - Retry only transient network/HTTP failures, not all errors. - Use exponential backoff and don’t sleep after the final attempt. - Use a list comprehension for readability/performance. - Add type hints, logging, constants, and basic JSON validation. - Avoid `== True`; use `is True` or a truthy check depending on API contract. Example refactor: ```python from __future__ import annotations import logging import time from typing import Any import requests logger = logging.getLogger(__name__) TIMEOUT = (3.05, 10) # connect time…

31.5s response5142 output tokens

Compare these answers side by side with other models →

Frequently asked questions

How much does the DeepSeek V4.1 Flash API cost?: On FastMetal, DeepSeek V4.1 Flash is billed per token in yen: ¥50.69 per 1M input tokens and ¥202.74 per 1M output tokens, before tax. Usage is drawn from a prepaid balance; there is no subscription or monthly fee.
Can I call DeepSeek V4.1 Flash with the OpenAI SDK?: Yes. Point base_url at https://api.fastmetal.ai/v1 and pass "deepseek-v4.1-flash" as the model; existing OpenAI-style code works unchanged, including streaming, tool calls and structured output.
What is the context window of DeepSeek V4.1 Flash?: 1,048,576 tokens, shared between the prompt and the response.
What do I need to try DeepSeek V4.1 Flash?: Create an account and add credit; the model is then available both in the browser chat and over the API. There is no contract or minimum spend.