DeepSeek V4.1 Flash Fast

deepseek/deepseek-v4.1-flash-fast

A chat model with a 1M-token context window, at $0.63 per million input tokens and $2.52 per million output tokens.

Details

Maker: deepseek
Kind: Chat
Context window: 1,048,576 tokens
Max output: 32,768 tokens
Input: $0.63 per million tokens
Cached input: $0.0147 per million tokens, 98% off
Cache write: Same as input
Output: $2.52 per million tokens
Capabilities: Reasoning, tool use, vision
Takes: Text, image
Returns: Text
Zero data retention: Yes, on every provider
No training on requests: Yes, on every provider
Released: 2026-09-29
Newer model: deepseek/deepseek-v4.1-flash-1017Released later by the same maker, costs no more, and lists the same capabilities. Compare the two

Description

Higher-throughput variant of DeepSeek V4.1 Flash for responsive coding, reasoning, and agentic workloads.

Call it

curl

curl https://phantom.codes/v1/chat/completions \
  -H "Authorization: Bearer $PHANTOM_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "deepseek/deepseek-v4.1-flash-fast",
    "messages": [
      {"role": "user", "content": "Hello"}
    ]
  }'

Set PHANTOM_KEY to your key. Any OpenAI client works with the base URL https://phantom.codes/v1.

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