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Ollama provides compatibility with the Anthropic Messages API to help connect existing applications to Ollama, including tools like Claude Code. For coding use cases, models like glm-4.7:cloud, minimax-m2.1:cloud, and qwen3-coder are recommended. Pull a model before use: 
ollama pull qwen3-coder
ollama pull glm-4.7:cloud

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Usage

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Environment variables

To use Ollama with tools that expect the Anthropic API (like Claude Code), set these environment variables: 
export ANTHROPIC_BASE_URL=http://localhost:11434
export ANTHROPIC_API_KEY=ollama  # required but ignored

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Simple /v1/messages example

basic.py
import anthropic

client = anthropic.Anthropic(
    base_url='http://localhost:11434',
    api_key='ollama',  # required but ignored
)

message = client.messages.create(
    model='qwen3-coder',
    max_tokens=1024,
    messages=[
        {'role': 'user', 'content': 'Hello, how are you?'}
    ]
)
print(message.content[0].text)

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Streaming example

streaming.py
import anthropic

client = anthropic.Anthropic(
    base_url='http://localhost:11434',
    api_key='ollama',
)

with client.messages.stream(
    model='qwen3-coder',
    max_tokens=1024,
    messages=[{'role': 'user', 'content': 'Count from 1 to 10'}]
) as stream:
    for text in stream.text_stream:
        print(text, end='', flush=True)

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Tool calling example

tools.py
import anthropic

client = anthropic.Anthropic(
    base_url='http://localhost:11434',
    api_key='ollama',
)

message = client.messages.create(
    model='qwen3-coder',
    max_tokens=1024,
    tools=[
        {
            'name': 'get_weather',
            'description': 'Get the current weather in a location',
            'input_schema': {
                'type': 'object',
                'properties': {
                    'location': {
                        'type': 'string',
                        'description': 'The city and state, e.g. San Francisco, CA'
                    }
                },
                'required': ['location']
            }
        }
    ],
    messages=[{'role': 'user', 'content': "What's the weather in San Francisco?"}]
)

for block in message.content:
    if block.type == 'tool_use':
        print(f'Tool: {block.name}')
        print(f'Input: {block.input}')

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Using with Claude Code

Claude Code can be configured to use Ollama as its backend: 
ANTHROPIC_BASE_URL=http://localhost:11434 ANTHROPIC_API_KEY=ollama claude --model qwen3-coder
Or set the environment variables in your shell profile: 
export ANTHROPIC_BASE_URL=http://localhost:11434
export ANTHROPIC_API_KEY=ollama
Then run Claude Code with any Ollama model: 
# Local models
claude --model qwen3-coder
claude --model gpt-oss:20b

# Cloud models
claude --model glm-4.7:cloud
claude --model minimax-m2.1:cloud

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Endpoints

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/v1/messages

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Supported features

  • Messages
  • Streaming
  • System prompts
  • Multi-turn conversations
  • Vision (images)
  • Tools (function calling)
  • Tool results
  • Thinking/extended thinking

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Supported request fields

  • model
  • max_tokens
  • messages
    • Text content
    • Image content (base64)
    • Array of content blocks
    • tool_use blocks
    • tool_result blocks
    • thinking blocks
  • system (string or array)
  • stream
  • temperature
  • top_p
  • top_k
  • stop_sequences
  • tools
  • thinking
  • tool_choice
  • metadata

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Supported response fields

  • id
  • type
  • role
  • model
  • content (text, tool_use, thinking blocks)
  • stop_reason (end_turn, max_tokens, tool_use)
  • usage (input_tokens, output_tokens)

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Streaming events

  • message_start
  • content_block_start
  • content_block_delta (text_delta, input_json_delta, thinking_delta)
  • content_block_stop
  • message_delta
  • message_stop
  • ping
  • error

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Models

Ollama supports both local and cloud models.

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Local models

Pull a local model before use: 
ollama pull qwen3-coder
Recommended local models:
  • qwen3-coder - Excellent for coding tasks
  • gpt-oss:20b - Strong general-purpose model

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Cloud models

Cloud models are available immediately without pulling:
  • glm-4.7:cloud - High-performance cloud model
  • minimax-m2.1:cloud - Fast cloud model

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Default model names

For tooling that relies on default Anthropic model names such as claude-3-5-sonnet, use ollama cp to copy an existing model name: 
ollama cp qwen3-coder claude-3-5-sonnet
Afterwards, this new model name can be specified in the model field: 
curl http://localhost:11434/v1/messages \
    -H "Content-Type: application/json" \
    -d '{
        "model": "claude-3-5-sonnet",
        "max_tokens": 1024,
        "messages": [
            {
                "role": "user",
                "content": "Hello!"
            }
        ]
    }'

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Differences from the Anthropic API

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Behavior differences

  • API key is accepted but not validated
  • anthropic-version header is accepted but not used
  • Token counts are approximations based on the underlying model’s tokenizer

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Not supported

The following Anthropic API features are not currently supported:
FeatureDescription
/v1/messages/count_tokensToken counting endpoint
tool_choiceForcing specific tool use or disabling tools
metadataRequest metadata (user_id)
Prompt cachingcache_control blocks for caching prefixes
Batches API/v1/messages/batches for async batch processing
Citationscitations content blocks
PDF supportdocument content blocks with PDF files
Server-sent errorserror events during streaming (errors return HTTP status)

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Partial support

FeatureStatus
Image contentBase64 images supported; URL images not supported
Extended thinkingBasic support; budget_tokens accepted but not enforced