OpenAI: gpt-oss-20b (free) — Free API

What is OpenAI: gpt-oss-20b (free)?

GPT-OSS 20B is OpenAI's open-weight 21B-parameter Mixture-of-Experts model with 3.6B active per forward pass, available free on OpenRouter (also on Groq, Cerebras, and Cloudflare). Supports reasoning level configuration, fine-tuning, and agentic capabilities — function calling, tool use, and structured outputs. Trained in OpenAI's Harmony response format. Released under Apache 2.0. The low active parameter count enables lower-latency inference on consumer or single-GPU hardware. 131K context window. Text-only. OpenAI-compatible. Free tier: 200 RPD on OpenRouter.

OpenAI: gpt-oss-20b (free) API Code Example

Paste your API key and run. See the config generator for Claude Code, Cursor, and more tools.

from openai import OpenAI

client = OpenAI(
    base_url="https://openrouter.ai/api/v1",
    api_key="YOUR_API_KEY"
)

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

import OpenAI from "openai";

const openai = new OpenAI({
  baseURL: "https://openrouter.ai/api/v1",
  apiKey: "YOUR_API_KEY",
});

const completion = await openai.chat.completions.create({
  model: "openai/gpt-oss-20b:free",
  messages: [{ role: "user", content: "Hello!" }],
});

console.log(completion.choices[0].message.content);

curl https://openrouter.ai/api/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "openai/gpt-oss-20b:free",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

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