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Model comparison

DeepSeek V4 Flash 0731 vs GPT OSS 20B (free)

DeepSeek V4 Flash 0731 (DeepSeek) and GPT OSS 20B (free) (OpenAI) side by side: what each costs per million tokens through Rapid Router, how much context each takes, what each supports, and where independent benchmarks place them. Same API, same key; switching is a one-string change.

DeepSeek V4 Flash 0731GPT OSS 20B (free)
Input price per 1M$0.060$0.030
Output price per 1M$0.180$0.140
Context window1M tokens131K tokens
Max output944K tokens16K tokens
Input typestexttext
Capabilitiestools, JSON, reasoningtools, reasoning
AuthorDeepSeekOpenAI

What a month costs on each

WorkloadDeepSeek V4 Flash 0731GPT OSS 20B (free)
Chatbot month (15M in, 4M out)$1.62$1.01
RAG month (40M in, 3M out)$2.94$1.62
Coding month (60M in, 10M out)$5.40$3.20

On a typical 75/25 input-output mix, GPT OSS 20B (free) costs less (about 36% less than DeepSeek V4 Flash 0731). DeepSeek V4 Flash 0731 takes the longer prompt at 1M tokens. Try your own numbers in the cost calculator.

Call either one

curl https://rapidrouter.ai/api/v1/chat/completions \
  -H "Authorization: Bearer $RAPIDROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model": "deepseek/deepseek-v4-flash-0731", "messages": [{"role": "user", "content": "Hello"}]}'

# the other one: change the model string
  -d '{"model": "openai/gpt-oss-20b:free", ...}'

Common questions

Which is cheaper, DeepSeek V4 Flash 0731 or GPT OSS 20B (free)?

GPT OSS 20B (free) is cheaper on a typical mix of 75% input and 25% output tokens, by about 36%. Through Rapid Router both are billed at the provider list price per million tokens.

Which has the larger context window?

DeepSeek V4 Flash 0731, at 1M tokens. GPT OSS 20B (free) offers 131K tokens.

Can I switch between DeepSeek V4 Flash 0731 and GPT OSS 20B (free) without changing code?

Yes. Both are callable at https://rapidrouter.ai/api/v1 with the same OpenAI-compatible request; only the model string changes (deepseek/deepseek-v4-flash-0731 or openai/gpt-oss-20b:free).

How do I pay for DeepSeek V4 Flash 0731 or GPT OSS 20B (free)?

Top up a Rapid Router balance by card in US dollars, and both models debit that balance per request.

More DeepSeek models: DeepSeek API pricing · More GPT: OpenAI API pricing