gpt-oss-120b

gpt-oss-120b 🇨🇭 Switzerland

gpt-oss-120b, the open-weight model by OpenAI: a mixture of experts with about 5 billion parameters per token. It reasons before it answers, at three levels (reasoning_effort low, medium or high); the reasoning counts as output tokens. Weights as released, MXFP4.

At a glance

Publisher	OpenAI
Architecture	Mixture of experts, 117 billion parameters, about 5 billion per token
Licence	Apache 2.0
Precision	MXFP4, 4 bits, as released by OpenAI
Context	32,768 tokens, prompt and answer together
Longest answer	`max_tokens` up to 8,192, reasoning included
Reads	Text
Calls tools	Yes
JSON schema	Yes
Reasons	Yes, always, at three levels: reasoning_effort "low", "medium" or "high". The reasoning counts as output tokens.
Runs in	🇨🇭 Switzerland
Status	Loaded: the first request answers without a start-up wait. Live state on Status.
Price	CHF 0.10 input · CHF 0.40 output, per million tokens, excluding VAT. All prices

Use it

curl https://api.aitokens.ch/v1/chat/completions \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-oss-120b",
    "messages": [{"role": "user", "content": "Summarise in one line: the meeting moves to Thursday at 10."}]
  }'

import os
from openai import OpenAI

client = OpenAI(base_url="https://api.aitokens.ch/v1", api_key=os.environ["API_KEY"])
answer = client.chat.completions.create(
    model="gpt-oss-120b",
    messages=[{"role": "user", "content": "Summarise in one line: the meeting moves to Thursday at 10."}],
)
print(answer.choices[0].message.content)

More in Quickstart and Chat completions.

Limits

Prompt and answer together stay within 32,768 tokens; beyond that the engine refuses the request with a 400 that says so.
The reasoning counts against max_tokens: a low cap can end the answer before it starts, with finish_reason: "length".
Text only: a request with an image gets a 400.
Served at 4 bits, which makes it faster and fits our machines; we write the precision of every model.
A request goes only to the zones your key allows; if the model has no machine there now, a 503 names the zones. It is never sent elsewhere.