GPT OSS 20B API

openai/gpt-oss-20b
OpenAI’s GPT OSS 20B offers flexible reasoning levels, agentic features, and robust coding support in an open-source, memory-efficient transformer.
Context
131K tokens
Input
$0.103155 / 1M tokens
Output
$0.41262 / 1M tokens
Released
Sep 9, 2025

How to use GPT OSS 20B API

Install any OpenAI-compatible SDK, point it at api.aimlapi.com/v1, and set the model to openai/gpt-oss-20b.
import requests

r = requests.post(
    "https://api.aimlapi.com/v1/chat/completions",
    headers={"Authorization": "Bearer " + AIMLAPI_KEY},
    json={
      "model": "openai/gpt-oss-20b",
      "messages": [
        {
          "role": "user",
          "content": "Hello!"
        }
      ]
    },
)
print(r.json())
const r = await fetch("https://api.aimlapi.com/v1/chat/completions", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.AIMLAPI_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "model": "openai/gpt-oss-20b",
    "messages": [
      {
        "role": "user",
        "content": "Hello!"
      }
    ]
  }),
});
console.log(await r.json());
curl -X POST https://api.aimlapi.com/v1/chat/completions \
  -H "Authorization: Bearer $AIMLAPI_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"openai/gpt-oss-20b","messages":[{"role":"user","content":"Hello!"}]}'

OpenAI-compatible — swap the base URL and it works with your existing SDK.

GPT OSS 20B API Pricing

TypePrice
Input
$0.103155 / 1M tokens
Output
$0.41262 / 1M tokens
Cached input
$0.0515775 / 1M tokens

GPT OSS 20B Benchmarks

BenchmarkScoreWhat it measuresSourceRetrieved
Humanity's Last Exam
10.9%
Expert-level questions across many domainsSourceJuly 13, 2026
GPQA Diamond
71.5%
Google-proof graduate science questions (hardest subset)SourceJuly 13, 2026
AIME 2025
91.7%
Competition mathematics (AIME), 2025SourceJuly 13, 2026
Intelligence
10
Composite score across standardised reasoning, knowledge and problem-solving evaluations, measured independently by Artificial AnalysisSourceSeptember 12, 2026
Math
62.3
Composite score across standardised mathematics evaluations, measured independently by Artificial AnalysisSourceSeptember 12, 2026

GPT OSS 20B vs other models

ModelInputOutputContextBest for
GPT OSS 20B
This page
$0.103155 / 1M tokens
$0.41262 / 1M tokens
131K tokens
Reasoning + agents
$6.5 / 1M tokens
$39 / 1M tokens
1.05M tokens
Reasoning + agents
$2.6 / 1M tokens
$13 / 1M tokens
1M tokens
Balanced coding + agents
$3.9 / 1M tokens
$19.5 / 1M tokens
1M tokens
Long-context, multimodal & agentic workflows
$0.65 / 1M tokens
$3.9 / 1M tokens
1.05M tokens
Reasoning + agents

Frequently asked questions

GPT OSS 20B has a 131,000 tokens context window and can return up to 131,072 tokens.

GPT OSS 20B takes text as input and returns text.

Use openai/gpt-oss-20b as the model id. Requests go to https://api.aimlapi.com/v1/chat/completions.

GPT OSS 20B became available on September 9, 2025.

GPT OSS 20B is priced at input $0.103155 / 1M tokens, output $0.41262 / 1M tokens, cached input $0.0515775 / 1M tokens.

Yes, GPT OSS 20B can stream responses as they are generated.

GPT OSS 20B was built by OpenAI.

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