Supported endpoints

Endpoint	Method	Docs
`/v1/messages`	POST	Messages

Using Claude Code with LM Studio

For a full walkthrough, see: Use Claude Code with LM Studio.

export ANTHROPIC_BASE_URL=http://localhost:1234
export ANTHROPIC_AUTH_TOKEN=lmstudio
claude --model openai/gpt-oss-20b

Authentication headers

When Require Authentication is enabled, LM Studio accepts both x-api-key and the standard Authorization: Bearer <token> header. To learn more about enabling auth in LM Studio, checkout Authentication.

Set the base URL to point to LM Studio

Point your Anthropic client (or any HTTP request) at your local LM Studio server.

Note: The following examples assume the server port is 1234.

cURL example

- curl https://api.anthropic.com/v1/messages \
+ curl http://localhost:1234/v1/messages \
   -H "Content-Type: application/json" \
+  -H "x-api-key: $LM_API_TOKEN" \
   -d '{
-    "model": "claude-4-5-sonnet",
+    "model": "ibm/granite-4-micro",
     "max_tokens": 256,
     "messages": [
       {"role": "user", "content": "Write a haiku about local LLMs."}
     ]
   }'

Python example

from anthropic import Anthropic

client = Anthropic(
    base_url="http://localhost:1234",
    api_key="lmstudio",
)

message = client.messages.create(
    max_tokens=1024,
    messages=[
        {
            "role": "user",
            "content": "Hello from LM Studio",
        }
    ],
    model="ibm/granite-4-micro",
)

print(message.content)

If you have not enabled Require Authentication, the x-api-key header is optional. For the Python example, you can also omit api_key when authentication is disabled.

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