gpt-oss-20b

OpenAI · Released August 2025 · Knowledge cutoff June 2024

gpt-oss-20b is an open-weight 21B parameter model released by OpenAI under the Apache 2.0 license. It uses a Mixture-of-Experts (MoE) architecture with 3.6B active parameters per forward pass, optimized for...

It is part of OpenAI's GPT family, where Sol, Luna and Terra mark the current generation's capability tiers and Pro servings trade speed for deeper computation.

Facts and pricing

Provider

OpenAI

Context window

131K tokens

Input price

0.33 credits / 1M tokens ($0.030 raw)

Output price

1.4 credits / 1M tokens ($0.13 raw)

Vision (image input)

No

Tool calling

Yes

Extended reasoning

No

Credits are what Zeplik bills: 1 credit = $0.10, computed from the raw provider rate with a 1.10x margin. Raw prices shown per 1M tokens.

What gpt-oss-20b is best for

• Balanced everyday work: writing, questions, brainstorming and summarization
• Tool use and agents: reliably calls functions, so it can search, run skills and drive workflows

Example prompts

Prompts that suit a general purpose model like gpt-oss-20b:

• Help me outline a talk about what I learned this year
• Compare these two paragraphs and tell me which is clearer and why
• Draft a polite reply declining this invitation
• Explain this concept with a concrete everyday analogy

OpenAI family

All 90 OpenAI models

Frequently asked questions

What is gpt-oss-20b?

gpt-oss-20b is an AI model by OpenAI. gpt-oss-20b is an open-weight 21B parameter model released by OpenAI under the Apache 2.0 license. It uses a Mixture-of-Experts (MoE) architecture with 3.6B active parameters per forward pass, optimized for...

How much does gpt-oss-20b cost on Zeplik?

Input tokens cost 0.33 credits per million and output tokens 1.4 credits per million (1 credit = $0.10; the raw provider rates are $0.030 and $0.13 per million). New accounts start with free credits.

How long can a conversation with gpt-oss-20b be?

gpt-oss-20b has a 131K-token context window (131,072 tokens), which covers the conversation plus any documents you attach.

Does gpt-oss-20b support images and tools?

gpt-oss-20b is text-only and supports tool calling.

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