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gpt-oss-20b

OpenAIReleased Aug 5, 2025

gpt-oss-20b is an open-weight 21B parameter model released by OpenAI under the Apache 2.0 license. It uses a Mixture-of-Experts (MoE) architecture with 3.6B active parameters per forward pass, optimized for...

Try in playground
Context window
131K tokens
Input
text
Output
text
Tokenizer
GPT
Knowledge cutoff
Jun 30, 2024
Released
Aug 5, 2025
Reasoning
always on

Pricing

Per 1M tokens. The provider price and our flat 3% fee are separate columns — what you pay is their sum.

Per 1M tokensProvider+ 3% feeYou pay
Input$0.029$0.0009$0.030
Output$0.140$0.0042$0.144

Benchmarks

Artificial Analysis

Intelligence index
14.9
Coding index
20.7
Agentic index
3.1

Design Arena

CategoryEloWin rateRank
Data vizmodels97839.7%#92
Websitesmodels89527.9%#107

Head-to-head preference voting. How we filter and rank

Supported parameters

  • frequency_penalty
  • include_reasoning
  • logit_bias
  • logprobs
  • max_tokens
  • min_p
  • presence_penalty
  • reasoning
  • repetition_penalty
  • response_format
  • seed
  • stop
  • structured_outputs
  • temperature
  • tool_choice
  • tools
  • top_k
  • top_logprobs
  • top_p

Call it

OpenAI-compatible: point your SDK at api.openkey.ai/v1 and use model openai/gpt-oss-20b.

Code sample language
curl https://api.openkey.ai/v1/chat/completions \
  -H "Authorization: Bearer $OPENKEY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-oss-20b",
    "messages": [{"role": "user", "content": "Hello"}]
  }'
import os
from openai import OpenAI

client = OpenAI(
    base_url="https://api.openkey.ai/v1",
    api_key=os.environ["OPENKEY_API_KEY"],
)

completion = client.chat.completions.create(
    model="openai/gpt-oss-20b",
    messages=[{"role": "user", "content": "Hello"}],
)
print(completion.choices[0].message.content)
import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://api.openkey.ai/v1",
  apiKey: process.env.OPENKEY_API_KEY,
});

const completion = await client.chat.completions.create({
  model: "openai/gpt-oss-20b",
  messages: [{ role: "user", content: "Hello" }],
});
console.log(completion.choices[0].message.content);

Questions

How much does gpt-oss-20b cost via API?
Through OpenKey, gpt-oss-20b costs $0.030 per 1M input tokens and $0.144 per 1M output tokens. That is the provider price ($0.029 / $0.140) plus a flat 3% fee — nothing else.
What is gpt-oss-20b's context window?
gpt-oss-20b accepts up to 131K tokens of context.
Is gpt-oss-20b OpenAI-compatible?
Yes. Send requests to OpenKey's /v1/chat/completions endpoint with model "openai/gpt-oss-20b" using any OpenAI SDK — only the base URL and API key change.
What inputs does gpt-oss-20b support?
gpt-oss-20b accepts text input and produces text output. Its knowledge cutoff is Jun 30, 2024.

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