gpt-oss-120b (free)
General purposeToolsOpenAI · Released August 2025 · Knowledge cutoff June 2024
gpt-oss-120b is an open-weight, 117B-parameter Mixture-of-Experts (MoE) language model from OpenAI designed for high-reasoning, agentic, and general-purpose production use cases. It activates 5.1B parameters per forward pass and is optimized...
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 credits / 1M tokens ($0 raw)
- Output price
- 0 credits / 1M tokens ($0 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.
Try gpt-oss-120b (free) now
What gpt-oss-120b (free) 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-120b (free):
- 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
| Model | Context | Input cr/M | Output cr/M | Released |
|---|---|---|---|---|
| GPT-5.6 Luna Pro | 1.1M | 11.0 | 66.0 | July 2026 |
| GPT-5.6 Luna | 1.1M | 11.0 | 66.0 | July 2026 |
| GPT-5.6 Terra Pro | 1.1M | 27.5 | 165 | July 2026 |
| GPT-5.6 Terra | 1.1M | 27.5 | 165 | July 2026 |
| GPT-5.6 Sol Pro | 1.1M | 55.0 | 330 | July 2026 |
| GPT-5.6 Sol | 1.1M | 55.0 | 330 | July 2026 |
| GPT Chat Latest | 400K | 55.0 | 330 | May 2026 |
| GPT-5.5 Pro | 1.1M | 330 | 1980 | April 2026 |
| GPT-5.5 | 1.1M | 55.0 | 330 | April 2026 |
| GPT-5.4 Image 2 | 272K | 88.0 | 165 | April 2026 |
Frequently asked questions
- What is gpt-oss-120b (free)?
- gpt-oss-120b (free) is an AI model by OpenAI. gpt-oss-120b is an open-weight, 117B-parameter Mixture-of-Experts (MoE) language model from OpenAI designed for high-reasoning, agentic, and general-purpose production use cases. It activates 5.1B parameters per forward pass and is optimized...
- How much does gpt-oss-120b (free) cost on Zeplik?
- Input tokens cost 0 credits per million and output tokens 0 credits per million (1 credit = $0.10; the raw provider rates are $0 and $0 per million). New accounts start with free credits.
- How long can a conversation with gpt-oss-120b (free) be?
- gpt-oss-120b (free) has a 131K-token context window (131,072 tokens), which covers the conversation plus any documents you attach.
- Does gpt-oss-120b (free) support images and tools?
- gpt-oss-120b (free) is text-only and supports tool calling.
Related models
GPT-5.6 Luna Pro is the same underlying model as [GPT-5.6 Luna](https://openrouter.ai/openai/gpt-5.6-luna), served with `reasoning.mode` set to `pro` for higher-quality responses on complex tasks. Learn more in OpenAI's docs: https://developers.openai.com/api/docs/guides/reasoning#reasoning-mode
GPT-5.6 Luna is a fast, cost-efficient model in OpenAI's GPT-5.6 series. It is suited for high-volume, latency-sensitive tasks such as chat, classification, and lightweight agentic workflows, providing capable reasoning for...
GPT-5.6 Terra Pro is the same underlying model as [GPT-5.6 Terra](https://openrouter.ai/openai/gpt-5.6-terra), served with `reasoning.mode` set to `pro` for higher-quality responses on complex tasks. Learn more in OpenAI's docs: https://developers.openai.com/api/docs/guides/reasoning#reasoning-mode
GPT-5.6 Terra is a balanced model in OpenAI's GPT-5.6 series, positioned between the flagship Sol tier and the cost-efficient Luna tier. It is suited for everyday coding, reasoning, and agentic...
GPT-5.6 Sol Pro is the same underlying model as [GPT-5.6 Sol](https://openrouter.ai/openai/gpt-5.6-sol), served with `reasoning.mode` set to `pro` for higher-quality responses on complex tasks. Learn more in OpenAI's docs: https://developers.openai.com/api/docs/guides/reasoning#reasoning-mode
GPT-5.6 Sol is the flagship model in OpenAI's GPT-5.6 series. It is suited for complex reasoning, coding, and agentic workflows, and is particularly strong at command-line and multi-step coding tasks...