o3

by openai · family o

Facts

Release date	2025-04-16
Retired date	—
Knowledge cutoff	—
Context (max)	200,000
Max output	100,000
Modalities	text, image → text
Aliases	—
Open weights	no
Description	o-series reasoning model; effort low/medium/high.

Unknown values are shown as —.

Intelligence Index v4.1.1: 31 · estimated · Source: Artificial Analysis (accessed 2026-08-20)

Offerings

Provider	Wire ID	Endpoint	Protocol	Status	Price (USD / Mtok)	Reasoning
NEAR AI Cloud	`openai/o3`	chat	openai-chat	ga	2.00 / 8.00	effort · default on · mandatory · returns reasoning_content
OpenAI	`o3`	v1-chat-completions	openai-chat	ga	2.00 / 8.00	effort · default on · mandatory · returns hidden
OpenAI	`o3`	v1-responses	openai-responses	ga	2.00 / 8.00	effort · default on · mandatory · returns hidden · round-trips encrypted_content
OpenRouter	`openai/o3`	chat-completions	openai-chat	ga	2.00 / 8.00	effort · default on · mandatory · returns reasoning_content · round-trips reasoning_content

Reasoning controls

NEAR AI Cloud· openai/o3· chat effort

reasoning_effort lowmedium●highxhighmax

effort · default on · mandatory · returns reasoning_content

OpenAI· o3· v1-chat-completions effort

reasoning_effort lowmedium●high

effort · default on · mandatory · returns hidden

Incompatible with: temperature, top_p

OpenAI· o3· v1-responses effort

reasoning.effort lowmedium●high

effort · default on · mandatory · returns hidden · round-trips encrypted_content

Incompatible with: temperature, top_p

OpenRouter· openai/o3· chat-completions effort

reasoning.effort lowmedium●highxhighmax

effort · default on · mandatory · returns reasoning_content · round-trips reasoning_content

Example requests

NEAR AI Cloud · openai-chat · openai/o3

curl 'https://cloud-api.near.ai/v1/chat/completions' \
  -H 'Authorization: Bearer <YOUR_API_KEY>' \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "openai/o3",
  "messages": [
    {
      "role": "user",
      "content": "Tell me about the weather."
    }
  ],
  "reasoning_effort": "medium"
}'

Python (requests)

import requests

resp = requests.post(
    "https://cloud-api.near.ai/v1/chat/completions",
    headers={
      "Authorization": "Bearer <YOUR_API_KEY>",
      "Content-Type": "application/json"
    },
    json={
      "model": "openai/o3",
      "messages": [
        {
          "role": "user",
          "content": "Tell me about the weather."
        }
      ],
      "reasoning_effort": "medium"
    },
)
print(resp.json())

TypeScript (fetch)

const resp = await fetch("https://cloud-api.near.ai/v1/chat/completions", {
  method: "POST",
  headers: {
    "Authorization": "Bearer <YOUR_API_KEY>",
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "model": "openai/o3",
    "messages": [
      {
        "role": "user",
        "content": "Tell me about the weather."
      }
    ],
    "reasoning_effort": "medium"
  }),
})
console.log(await resp.json())

OpenAI · openai-chat · o3

curl 'https://api.openai.com/v1/chat/completions' \
  -H 'Authorization: Bearer <YOUR_API_KEY>' \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "o3",
  "messages": [
    {
      "role": "user",
      "content": "Tell me about the weather."
    }
  ],
  "reasoning_effort": "medium"
}'

Python (requests)

import requests

resp = requests.post(
    "https://api.openai.com/v1/chat/completions",
    headers={
      "Authorization": "Bearer <YOUR_API_KEY>",
      "Content-Type": "application/json"
    },
    json={
      "model": "o3",
      "messages": [
        {
          "role": "user",
          "content": "Tell me about the weather."
        }
      ],
      "reasoning_effort": "medium"
    },
)
print(resp.json())

TypeScript (fetch)

const resp = await fetch("https://api.openai.com/v1/chat/completions", {
  method: "POST",
  headers: {
    "Authorization": "Bearer <YOUR_API_KEY>",
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "model": "o3",
    "messages": [
      {
        "role": "user",
        "content": "Tell me about the weather."
      }
    ],
    "reasoning_effort": "medium"
  }),
})
console.log(await resp.json())

Reported incompatible with thinking controls: temperature, top_p.

OpenAI · openai-responses · o3

curl 'https://api.openai.com/v1/responses' \
  -H 'Authorization: Bearer <YOUR_API_KEY>' \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "o3",
  "input": "Tell me about the weather.",
  "reasoning": {
    "effort": "medium"
  }
}'

Python (requests)

import requests

resp = requests.post(
    "https://api.openai.com/v1/responses",
    headers={
      "Authorization": "Bearer <YOUR_API_KEY>",
      "Content-Type": "application/json"
    },
    json={
      "model": "o3",
      "input": "Tell me about the weather.",
      "reasoning": {
        "effort": "medium"
      }
    },
)
print(resp.json())

TypeScript (fetch)

const resp = await fetch("https://api.openai.com/v1/responses", {
  method: "POST",
  headers: {
    "Authorization": "Bearer <YOUR_API_KEY>",
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "model": "o3",
    "input": "Tell me about the weather.",
    "reasoning": {
      "effort": "medium"
    }
  }),
})
console.log(await resp.json())

⚠ Responses include encrypted_content artifacts — pass them back unmodified on subsequent turns (dropping them triggers 400s or quality loss).
Reported incompatible with thinking controls: temperature, top_p.

OpenRouter · openai-chat · openai/o3

curl 'https://openrouter.ai/api/v1/chat/completions' \
  -H 'Authorization: Bearer <YOUR_API_KEY>' \
  -H 'Content-Type: application/json' \
  -d '{
  "model": "openai/o3",
  "messages": [
    {
      "role": "user",
      "content": "Tell me about the weather."
    }
  ],
  "reasoning": {
    "effort": "medium"
  }
}'

Python (requests)

import requests

resp = requests.post(
    "https://openrouter.ai/api/v1/chat/completions",
    headers={
      "Authorization": "Bearer <YOUR_API_KEY>",
      "Content-Type": "application/json"
    },
    json={
      "model": "openai/o3",
      "messages": [
        {
          "role": "user",
          "content": "Tell me about the weather."
        }
      ],
      "reasoning": {
        "effort": "medium"
      }
    },
)
print(resp.json())

TypeScript (fetch)

const resp = await fetch("https://openrouter.ai/api/v1/chat/completions", {
  method: "POST",
  headers: {
    "Authorization": "Bearer <YOUR_API_KEY>",
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "model": "openai/o3",
    "messages": [
      {
        "role": "user",
        "content": "Tell me about the weather."
      }
    ],
    "reasoning": {
      "effort": "medium"
    }
  }),
})
console.log(await resp.json())

⚠ Responses include reasoning_content artifacts — pass them back unmodified on subsequent turns (dropping them triggers 400s or quality loss).