GPT OSS 120B API

openai/gpt-oss-120b
GPT OSS 120B is a large-scale open-source language model with 120 billion parameters, designed for advanced reasoning, code generation, and extended context processing.
Context
128K tokens
Input
$0.48139 / 1M tokens
Output
$1.30663 / 1M tokens
Released
Sep 9, 2025

How to use GPT OSS 120B API

Install any OpenAI-compatible SDK, point it at api.aimlapi.com/v1, and set the model to openai/gpt-oss-120b.
import requests

r = requests.post(
    "https://api.aimlapi.com/v1/chat/completions",
    headers={"Authorization": "Bearer " + AIMLAPI_KEY},
    json={
      "model": "openai/gpt-oss-120b",
      "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-120b",
    "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-120b","messages":[{"role":"user","content":"Hello!"}]}'

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

GPT OSS 120B API Pricing

TypePrice
Input
$0.48139 / 1M tokens
Output
$1.30663 / 1M tokens
Cached input
$0.48139 / 1M tokens

GPT OSS 120B Benchmarks

BenchmarkScoreWhat it measuresSourceRetrieved
Humanity's Last Exam
14.9%
Expert-level questions across many domainsSourceJuly 8, 2026
GPQA Diamond
80.1%
Google-proof graduate science questions (hardest subset)SourceJuly 8, 2026
AIME 2025
92.5%
Competition mathematics (AIME), 2025SourceJuly 8, 2026
Intelligence
12.3
Composite score across standardised reasoning, knowledge and problem-solving evaluations, measured independently by Artificial AnalysisSourceSeptember 12, 2026
Coding
30.4
Composite score across standardised coding evaluations, measured independently by Artificial AnalysisSourceSeptember 12, 2026
Math
93.4
Composite score across standardised mathematics evaluations, measured independently by Artificial AnalysisSourceSeptember 12, 2026

GPT OSS 120B vs other models

ModelInputOutputContextBest for
GPT OSS 120B
This page
$0.48139 / 1M tokens
$1.30663 / 1M tokens
128K tokens
Reasoning + agents
$6.5 / 1M tokens
$39 / 1M tokens
1M 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
1M tokens
Reasoning + agents

Frequently asked questions

GPT OSS 120B has a 131,000 tokens context window and can return up to 131,072 tokens.

GPT OSS 120B takes text as input and returns text.

Use openai/gpt-oss-120b as the model id. Requests go to https://api.aimlapi.com/v1/chat/completions.

GPT OSS 120B became available on September 9, 2025.

GPT OSS 120B is priced at input $0.48139 / 1M tokens, output $1.30663 / 1M tokens, cached input $0.48139 / 1M tokens.

Yes, GPT OSS 120B can stream responses as they are generated.

GPT OSS 120B was built by OpenAI.

It is accessed via the endpoint https://api.aimlapi.com/v1/chat/completions, not directly through OpenAI's own API.

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