# GPT-OSS 120B API — pricing & specs

OpenAI's open-weight model in the GPT-OSS line — a large (~120B-class) open-weights release for reasoning and coding, offered here through the OpenAI-compatible API. On KeepRouter, GPT-OSS 120B costs $0.15 per 1M input tokens and $0.60 per 1M output tokens, billed at cost with no markup and no monthly fee (e.g. a 1,000-token prompt with a 500-token reply costs about $0.0004). Call it through the OpenAI- or Anthropic-compatible API with the model id `gpt-oss-120b`.

| Spec | Value |
|---|---|
| Maker | OpenAI |
| Modality | Text |
| Input price | $0.15 per 1M tokens |
| Output price | $0.60 per 1M tokens |
| Capabilities | Streaming, Tool / function calling |
| APIs | OpenAI-compatible, Anthropic-compatible |
| Model id | `gpt-oss-120b` |

## Call it via the OpenAI API (cURL)

```bash
curl https://keeprouter.com/v1/chat/completions \
  -H "Authorization: Bearer $KEEPROUTER_KEY" -H "Content-Type: application/json" \
  -d '{"model":"gpt-oss-120b","messages":[{"role":"user","content":"Hello"}]}'
```

## Python

```python
from openai import OpenAI
client = OpenAI(base_url="https://keeprouter.com/v1", api_key="$KEEPROUTER_KEY")
r = client.chat.completions.create(model="gpt-oss-120b", messages=[{"role":"user","content":"Hello"}])
```

## JavaScript

```js
import OpenAI from "openai";
const client = new OpenAI({ baseURL: "https://keeprouter.com/v1", apiKey: process.env.KEEPROUTER_KEY });
const r = await client.chat.completions.create({ model: "gpt-oss-120b", messages: [{ role: "user", content: "Hello" }] });
```

## Frequently asked questions

### How much does GPT-OSS 120B cost on KeepRouter?

GPT-OSS 120B is $0.15 per 1M input tokens and $0.60 per 1M output tokens, billed at cost with no markup and no monthly fee.

### How much does a typical GPT-OSS 120B request cost?

On KeepRouter, a 1,000-token prompt with a 500-token reply costs about $0.0004 — billed at cost with no markup.

### Who makes GPT-OSS 120B?

GPT-OSS 120B is made by OpenAI. KeepRouter provides it through one OpenAI- and Anthropic-compatible API.

### How do I call GPT-OSS 120B via API?

Point your OpenAI- or Anthropic-compatible client at KeepRouter and set the model to "gpt-oss-120b". It works with the OpenAI SDK, the Anthropic SDK, and Claude Code — no provider-specific SDK needed.

### Does GPT-OSS 120B support streaming?

Yes. KeepRouter streams GPT-OSS 120B responses over both the OpenAI and Anthropic APIs.

### Does GPT-OSS 120B support tool (function) calling?

Yes. KeepRouter passes tool calls through to GPT-OSS 120B and translates them between the OpenAI and Anthropic formats.

## Guides

- [Call GPT-OSS 120B with the OpenAI SDK](https://keeprouter.com/use-cases/openai-sdk.md)
- [Use GPT-OSS 120B in Claude Code](https://keeprouter.com/use-cases/claude-code.md)

## Related models from OpenAI

- [GPT-4o](https://keeprouter.com/models/gpt-4o.md) — $2.50 per 1M input tokens and $10 per 1M output tokens
- [GPT-5.5](https://keeprouter.com/models/gpt-5.5.md) — $5 per 1M input tokens and $30 per 1M output tokens

## More

- [All models & pricing](https://keeprouter.com/models.md)
- [Quickstart](https://keeprouter.com/docs/quickstart.md)
- [Get an API key](https://keeprouter.com/login)

_Prices as of 2026-07-05._