DeepSeek V4.1 Flash Fast vs GPT OSS 20B
As of November 12, 2026, DeepSeek V4.1 Flash Fast costs 245% more per input token than GPT OSS 20B ($0.05 vs $0.0145 per 1M) and has a 1M-token context window versus 128K.
DeepSeek V4.1 Flash Fast vs GPT OSS 20B side by side
| DeepSeek V4.1 Flash Fast | GPT OSS 20B | |
|---|---|---|
| Input, per 1M tokens | $0.05 | $0.0145 |
| Output, per 1M tokens | $0.15 | $0.07 |
| Cache read, per 1M tokens | $0.003 | – |
| Cache write, per 1M tokens | – | – |
| Context window | 1,048,576 tokens | 131,072 tokens |
| Max output | 262,144 tokens | 32,768 tokens |
| Image input | No | – |
| Tool calling | Yes | Yes |
| Structured output (JSON) | Yes | Yes |
| Prompt caching | Yes | Yes |
| Reasoning | Yes | Yes |
| Providers on LiteLLM | 4 | 17 |
| Price shown is from | Refuseless | Darkbloom |
| Added to LiteLLM | September 29, 2026 | August 2025 |
Cheapest provider for each
- DeepSeek V4.1 Flash Fast: Refuseless at $0.05 input and $0.15 output per 1M tokens (
refuseless/deepseek-v4.1-flash-fast) - GPT OSS 20B: Darkbloom at $0.0145 input and $0.07 output per 1M tokens (
darkbloom/gpt-oss-20b)
When to pick which
Pick DeepSeek V4.1 Flash Fast for
- Larger context window: 1,048,576 vs 131,072 tokens.
- Returns up to 262,144 tokens per response, vs 32,768.
Pick GPT OSS 20B for
- Costs 71% less per input token: $0.0145 vs $0.05 per 1M.
- Available from 17 providers through LiteLLM, vs 4.
From differences in the data above only; where the data is equal, no reason is given.
Call DeepSeek V4.1 Flash Fast or GPT OSS 20B with LiteLLM
Both use the OpenAI format through LiteLLM, so switching is a model name change. Set each provider's API key in the environment first.
from litellm import completion
messages = [{"role": "user", "content": "Hello!"}]
# DeepSeek V4.1 Flash Fast
response = completion(model="refuseless/deepseek-v4.1-flash-fast", messages=messages)
# GPT OSS 20B
response = completion(model="darkbloom/gpt-oss-20b", messages=messages)
# DeepSeek V4.1 Flash Fast, falling back to GPT OSS 20B if the call fails
response = completion(model="refuseless/deepseek-v4.1-flash-fast", messages=messages, fallbacks=["darkbloom/gpt-oss-20b"])FAQ
Which is cheaper, DeepSeek V4.1 Flash Fast or GPT OSS 20B?
GPT OSS 20B is cheaper at 3 input tokens per output token: $0.02838 per 1M tokens blended ($0.0145 input, $0.07 output), versus $0.075 ($0.05 and $0.15) for DeepSeek V4.1 Flash Fast, as of November 12, 2026.
Which has the larger context window, DeepSeek V4.1 Flash Fast or GPT OSS 20B?
DeepSeek V4.1 Flash Fast has the larger context window: 1,048,576 tokens, versus 131,072 for GPT OSS 20B.
Can I switch from DeepSeek V4.1 Flash Fast to GPT OSS 20B without changing my code?
Yes. Through LiteLLM both use the OpenAI format, so switching means changing the model name from "refuseless/deepseek-v4.1-flash-fast" to "darkbloom/gpt-oss-20b", or pointing a LiteLLM gateway model alias at the other model. You can also use one as a fallback for the other.