Model comparison
GPT OSS 20B (free) vs Grok Build 0.1
GPT OSS 20B (free) (OpenAI) and Grok Build 0.1 (xAI) 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.
| GPT OSS 20B (free) | Grok Build 0.1 | |
|---|---|---|
| Input price per 1M | $0.030 | $1.00 |
| Output price per 1M | $0.140 | $2.00 |
| Context window | 131K tokens | 256K tokens |
| Max output | 16K tokens | 256K tokens |
| Input types | text | text, image, pdf |
| Capabilities | tools, reasoning | tools, JSON, vision, reasoning |
| Author | OpenAI | xAI |
What a month costs on each
| Workload | GPT OSS 20B (free) | Grok Build 0.1 |
|---|---|---|
| Chatbot month (15M in, 4M out) | $1.01 | $23.00 |
| RAG month (40M in, 3M out) | $1.62 | $46.00 |
| Coding month (60M in, 10M out) | $3.20 | $80.00 |
On a typical 75/25 input-output mix, GPT OSS 20B (free) costs less (about 95% less than Grok Build 0.1). Grok Build 0.1 takes the longer prompt at 256K 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": "openai/gpt-oss-20b:free", "messages": [{"role": "user", "content": "Hello"}]}'
# the other one: change the model string
-d '{"model": "x-ai/grok-build-0.1", ...}'Common questions
Which is cheaper, GPT OSS 20B (free) or Grok Build 0.1?
GPT OSS 20B (free) is cheaper on a typical mix of 75% input and 25% output tokens, by about 95%. Through Rapid Router both are billed at the provider list price per million tokens.
Which has the larger context window?
Grok Build 0.1, at 256K tokens. GPT OSS 20B (free) offers 131K tokens.
Can I switch between GPT OSS 20B (free) and Grok Build 0.1 without changing code?
Yes. Both are callable at https://rapidrouter.ai/api/v1 with the same OpenAI-compatible request; only the model string changes (openai/gpt-oss-20b:free or x-ai/grok-build-0.1).
How do I pay for GPT OSS 20B (free) or Grok Build 0.1?
Top up a Rapid Router balance by card in US dollars, and both models debit that balance per request.
More GPT models: OpenAI API pricing · More Grok: xAI API pricing