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Free · GPT-OSS 20B

Free GPT-OSS API.
No key. No subscription.

OpenAI's GPT-OSS — the only open-weights models OpenAI ever released. The 20B variant, 128K context, hosted free on NVIDIA and called through BlockRun. (NVIDIA retired its free 120B hosting on 2026-09-03; calls to it now redirect.)

Try in 10 secondsSee all 6 waysWant Claude / GPT-5? Pay-per-call →
Quickstart · 10 seconds

Try it now.

No API key. No wallet. No signup. Paste this into any terminal — the response streams back from GPT-OSS 20B, routed through BlockRun.

curl
curl https://blockrun.ai/api/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "nvidia/gpt-oss-20b",
    "messages": [{"role": "user", "content": "Explain prompt caching in two sentences"}]
  }'
See all 6 waysFull API reference →
Spotlight
GPT-OSS 20B
nvidia/gpt-oss-20b
Context
128K
Price
free
Best for
coding
Six ways to call it

6 ways to use GPT-OSS free.

BlockRun is the access layer. Pick the surface that matches how you build — terminal, notebook, IDE, agent runtime — and the same free models work everywhere.

  1. 01

    cURL

    no key, no wallet, paste in any terminal

    Learn more →
    shell
    curl https://blockrun.ai/api/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "nvidia/gpt-oss-20b",
    "messages": [{"role": "user", "content": "Explain prompt caching in two sentences"}]
  }'
  2. 02

    Python SDK

    pip install blockrun-llm — or any OpenAI-compatible client

    Learn more →
    python
    # Works with the OpenAI SDK — no key required for free models
from openai import OpenAI

client = OpenAI(
    base_url="https://blockrun.ai/api/v1",
    api_key="not-needed-for-free-models",
)

response = client.chat.completions.create(
    model="nvidia/gpt-oss-20b",
    messages=[{"role": "user", "content": "Explain prompt caching in two sentences"}],
)
print(response.choices[0].message.content)
  3. 03

    ClawRouter

    smart router for OpenClaw / Claude Code — auto-picks free models when possible

    Learn more →
    shell
    # Install once
npm install -g @blockrun/clawrouter

# Then point any OpenAI-compatible client at the local proxy.
# ClawRouter routes to nvidia/gpt-oss-20b (or the cheapest capable model)
# without changing your code.
  4. 04

    TypeScript SDK

    npm install @blockrun/llm — or any OpenAI-compatible client

    Learn more →
    typescript
    // Works with the OpenAI SDK — no key required for free models
import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://blockrun.ai/api/v1",
  apiKey: "not-needed-for-free-models",
});

const r = await client.chat.completions.create({
  model: "nvidia/gpt-oss-20b",
  messages: [{ role: "user", content: "Explain prompt caching in two sentences" }],
});
console.log(r.choices[0].message.content);
  5. 05

    Claude Code MCP

    19 tools for Claude Code, Cursor & ChatGPT — call any free model from inside your editor

    Learn more →
    shell
    # Add the BlockRun MCP server (Claude Code, Cursor, or ChatGPT desktop)
claude mcp add blockrun -s user -- npx -y @blockrun/mcp@latest

# Then call from inside the editor:
#   blockrun_chat(model="nvidia/gpt-oss-20b", messages=[{role:"user", content:"…"}])
  6. 06

    Franklin Agent

    the AI agent with a wallet — free OSS models for routine tasks, paid models on demand

    Learn more →
    shell
    # Install Franklin Agent
npm i -g @blockrun/franklin

# Run with this model
franklin start --model nvidia/gpt-oss-20b -p "Summarize the README"
Trust / Defaults

We don't share
your data.

Your prompt goes to the AI provider you picked. Nothing else, nowhere else. No training, no retention beyond the request, no profile linking.

Read the privacy policyTerms →
We don't share your data
No training, no retention beyond the request. Your prompt is forwarded only to the AI provider you select.
No accounts, no sign-up
Wallet in, prompt out. Pseudonymous by default — no email, no phone number, no identity documents.
Open-source SDKs, MIT
Read the code, audit the wire format, run it yourself. @blockrun/llm and blockrun-llm on npm and PyPI.
When free isn't enough

Want Claude, GPT-5,
or Gemini too?

No subscription. No monthly minimum. Pay per call in USDC via x402 — works the same endpoint, same SDK, same model IDs. Connect a wallet, top up $5, call any frontier model. No credit card.

See pay-per-call pricingGet started
FAQ

Everything you might
be wondering.

Is this a real OpenAI model?
Yes — GPT-OSS is OpenAI's open-weights release. The model files are public; NVIDIA hosts inference free on build.nvidia.com, and BlockRun routes calls to it without auth.
How does it compare to GPT-5?
GPT-OSS 20B is closer to GPT-3.5 class than current frontier — but it's free, fast, and runs on a permissive license. For frontier quality, use GPT-5.5 on the paid tier.
Why is it not in the public catalog?
Hidden from /v1/models for privacy reasons (NVIDIA's free tier may use prompts for service improvement). Still callable by ID for legacy / direct integrations.
What happened to GPT-OSS 120B?
NVIDIA retired its free hosting of gpt-oss-120b on 2026-09-03 (the upstream now answers 410 Gone). Calls to nvidia/gpt-oss-120b — and to the bare name gpt-oss-120b — are redirected to nvidia/nemotron-3-super-120b, a free 120B-class model, so pinned integrations keep working. The 20B is unaffected.