Thinking

Thinking-capable models emit a thinking field that separates their reasoning trace from the final answer. Use this capability to audit model steps, animate the model thinking in a UI, or hide the trace entirely when you only need the final response. See the full list of thinking models.

Discover a model’s thinking controls

Thinking controls vary by model. Use /api/show to discover the values a model supports and the value Ollama uses by default:

curl http://localhost:11434/api/show -d '{
  "model": "gpt-oss"
}'

The response includes a top-level thinking object:

{
  "thinking": {
    "values": ["low", "medium", "high"],
    "default": "medium"
  }
}

values can contain booleans (true or false) for on/off controls. It can also contain model-defined strings for named levels.
default is used when think is not set.
values: [false] means the model does not support thinking.
If thinking is omitted, the model has no thinking metadata. The model might conduct thinking based on its existing behavior.

Enable thinking in API calls

Set the think field on a chat or generate request:

true: request thinking output.
false: request no thinking output, if the model permits it.
null: use the model default.
A string: select a supported level from thinking.values. Use the exact value from /api/show. Numbers are not supported.

If the model resolves named levels from /api/show metadata, Ollama applies supported names exactly. Unsupported names use the model default. The reasoning output and answer use separate fields. Chat returns message.thinking and message.content. Generate returns thinking and response.

cURL
Python
JavaScript

curl http://localhost:11434/api/chat -d '{
  "model": "qwen3",
  "messages": [{
    "role": "user",
    "content": "How many letter r are in strawberry?"
  }],
  "think": true,
  "stream": false
}'

from ollama import chat

response = chat(
  model='qwen3',
  messages=[{'role': 'user', 'content': 'How many letter r are in strawberry?'}],
  think=True,
  stream=False,
)

print('Thinking:\n', response.message.thinking)
print('Answer:\n', response.message.content)

import ollama from 'ollama'

const response = await ollama.chat({
  model: 'deepseek-r1',
  messages: [{ role: 'user', content: 'How many letter r are in strawberry?' }],
  think: true,
  stream: false,
})

console.log('Thinking:\n', response.message.thinking)
console.log('Answer:\n', response.message.content)

Stream the reasoning trace

Thinking streams interleave reasoning tokens before answer tokens. Detect the first thinking chunk to render a “thinking” section, then switch to the final reply once message.content arrives.

Python
JavaScript

from ollama import chat

stream = chat(
  model='qwen3',
  messages=[{'role': 'user', 'content': 'What is 17 × 23?'}],
  think=True,
  stream=True,
)

in_thinking = False

for chunk in stream:
  if chunk.message.thinking and not in_thinking:
    in_thinking = True
    print('Thinking:\n', end='')

  if chunk.message.thinking:
    print(chunk.message.thinking, end='')
  elif chunk.message.content:
    if in_thinking:
      print('\n\nAnswer:\n', end='')
      in_thinking = False
    print(chunk.message.content, end='')

import ollama from 'ollama'

async function main() {
  const stream = await ollama.chat({
    model: 'qwen3',
    messages: [{ role: 'user', content: 'What is 17 × 23?' }],
    think: true,
    stream: true,
  })

  let inThinking = false

  for await (const chunk of stream) {
    if (chunk.message.thinking && !inThinking) {
      inThinking = true
      process.stdout.write('Thinking:\n')
    }

    if (chunk.message.thinking) {
      process.stdout.write(chunk.message.thinking)
    } else if (chunk.message.content) {
      if (inThinking) {
        process.stdout.write('\n\nAnswer:\n')
        inThinking = false
      }
      process.stdout.write(chunk.message.content)
    }
  }
}

main()

Get started

Capabilities

More information

Discover a model’s thinking controls

Enable thinking in API calls

Stream the reasoning trace

​Discover a model’s thinking controls

​Enable thinking in API calls

​Stream the reasoning trace

Discover a model’s thinking controls

Enable thinking in API calls

Stream the reasoning trace