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GPT OSS 20B

GPT OSS 20B is OpenAI's smaller open-weight model with roughly 21 billion total parameters and 3.6 billion active per token, designed for low-latency, agentic, and on-device workloads.

ReasoningTool Use
index.ts
import { streamText } from 'ai'


const result = streamText({
  model: 'openai/gpt-oss-20b',
  prompt: 'Why is the sky blue?'
})
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Frequently Asked Questions

  • How does GPT OSS 20B compare to gpt-oss-120b?

    Both share the same MoE architecture, 131.1K tokens context, and Apache 2.0 license. GPT OSS 20B activates fewer parameters per token (about 3.6 billion versus 5.1 billion), runs on a 16 GB device, and matches o3-mini on common benchmarks. gpt-oss-120b approaches o4-mini on harder reasoning tasks but costs more to serve.

  • What hardware is GPT OSS 20B designed for?

    OpenAI designed it to run on a single device with 16 GB of memory, including consumer-grade hardware. Weights ship natively quantized in MXFP4. When used through AI Gateway you don't manage hardware — requests route to bedrock, fireworks, groq, deepinfra, togetherai, novita, parasail.

  • Does GPT OSS 20B support tool calling and structured outputs?

    Yes. GPT OSS 20B supports native function calling, structured outputs, and long chain-of-thought reasoning. You can also select a reasoning level (low, mid, or high) per request, similar to the o-series.

  • What license is GPT OSS 20B released under?

    Apache 2.0. You can inspect, deploy, fine-tune, and redistribute the weights without OpenAI licensing restrictions. Fine-tuning happens outside AI Gateway since AI Gateway serves models as a managed API.

  • What context window does GPT OSS 20B support?

    131.1K tokens, sufficient for long documents, multi-turn agentic sessions, and transcript-heavy workloads.

  • Can I call GPT OSS 20B through the AI SDK?

    Yes. GPT OSS 20B is available through AI Gateway via the AI SDK as well as Chat Completions, Responses, and Messages-compatible API formats. Use openai/gpt-oss-20b as the model identifier.

  • Is Zero Data Retention available for GPT OSS 20B?

    Yes, Zero Data Retention is available for this model. Zero Data Retention is offered on a per-provider basis. See https://vercel.com/docs/ai-gateway/capabilities/zdr for details.