Messages

Create messages using the Anthropic-compatible API format.

Endpoint

POST https://api.scalellm.dev/v1/messages

Examples

Python
JavaScript
cURL

from anthropic import Anthropic

client = Anthropic(
    base_url="https://api.scalellm.dev",
    api_key="sk_your_key"
)

message = client.messages.create(
    model="claude-sonnet-4.5",
    max_tokens=1024,
    messages=[
        {"role": "user", "content": "Hello, Claude!"}
    ]
)

print(message.content[0].text)

import Anthropic from '@anthropic-ai/sdk';

const client = new Anthropic({
  baseURL: 'https://api.scalellm.dev',
  apiKey: 'sk_your_key'
});

const message = await client.messages.create({
  model: 'claude-sonnet-4.5',
  max_tokens: 1024,
  messages: [
    { role: 'user', content: 'Hello, Claude!' }
  ]
});

console.log(message.content[0].text);

curl https://api.scalellm.dev/v1/messages \
  -H "Authorization: Bearer sk_your_key" \
  -H "Content-Type: application/json" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-sonnet-4.5",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "Hello, Claude!"}
    ]
  }'

Request Body

Parameter	Type	Required	Description
`model`	string	Yes	Model ID (e.g., `claude-sonnet-4.5`)
`messages`	array	Yes	Array of message objects
`max_tokens`	integer	Yes	Maximum tokens to generate
`system`	string	No	System prompt
`temperature`	number	No	Sampling temperature (0-1)
`top_p`	number	No	Nucleus sampling parameter
`top_k`	integer	No	Top-k sampling parameter
`stream`	boolean	No	Enable streaming responses
`stop_sequences`	array	No	Custom stop sequences

Message Object

Field	Type	Description
`role`	string	Either `user` or `assistant`
`content`	string or array	Text content or content blocks

Response

{
  "id": "msg_01XYZ...",
  "type": "message",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "Hello! How can I help you today?"
    }
  ],
  "model": "claude-sonnet-4.5",
  "stop_reason": "end_turn",
  "usage": {
    "input_tokens": 12,
    "output_tokens": 15
  }
}

Response Fields

Field	Type	Description
`id`	string	Unique message ID
`type`	string	Always `message`
`role`	string	Always `assistant`
`content`	array	Array of content blocks
`model`	string	Model used
`stop_reason`	string	Why generation stopped (`end_turn`, `max_tokens`, `stop_sequence`)
`usage`	object	Token usage statistics

System Prompts

Python
JavaScript
cURL

from anthropic import Anthropic

client = Anthropic(
    base_url="https://api.scalellm.dev",
    api_key="sk_your_key"
)

message = client.messages.create(
    model="claude-sonnet-4.5",
    max_tokens=1024,
    system="You are a helpful coding assistant.",
    messages=[
        {"role": "user", "content": "Write a Python hello world."}
    ]
)

print(message.content[0].text)

import Anthropic from '@anthropic-ai/sdk';

const client = new Anthropic({
  baseURL: 'https://api.scalellm.dev',
  apiKey: 'sk_your_key'
});

const message = await client.messages.create({
  model: 'claude-sonnet-4.5',
  max_tokens: 1024,
  system: 'You are a helpful coding assistant.',
  messages: [
    { role: 'user', content: 'Write a Python hello world.' }
  ]
});

console.log(message.content[0].text);

curl https://api.scalellm.dev/v1/messages \
  -H "Authorization: Bearer sk_your_key" \
  -H "Content-Type: application/json" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-sonnet-4.5",
    "max_tokens": 1024,
    "system": "You are a helpful coding assistant.",
    "messages": [
      {"role": "user", "content": "Write a Python hello world."}
    ]
  }'

Multi-turn Conversations

Python
JavaScript
cURL

from anthropic import Anthropic

client = Anthropic(
    base_url="https://api.scalellm.dev",
    api_key="sk_your_key"
)

message = client.messages.create(
    model="claude-sonnet-4.5",
    max_tokens=1024,
    messages=[
        {"role": "user", "content": "What is 2+2?"},
        {"role": "assistant", "content": "2+2 equals 4."},
        {"role": "user", "content": "And what is that times 10?"}
    ]
)

print(message.content[0].text)

import Anthropic from '@anthropic-ai/sdk';

const client = new Anthropic({
  baseURL: 'https://api.scalellm.dev',
  apiKey: 'sk_your_key'
});

const message = await client.messages.create({
  model: 'claude-sonnet-4.5',
  max_tokens: 1024,
  messages: [
    { role: 'user', content: 'What is 2+2?' },
    { role: 'assistant', content: '2+2 equals 4.' },
    { role: 'user', content: 'And what is that times 10?' }
  ]
});

console.log(message.content[0].text);

curl https://api.scalellm.dev/v1/messages \
  -H "Authorization: Bearer sk_your_key" \
  -H "Content-Type: application/json" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-sonnet-4.5",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "What is 2+2?"},
      {"role": "assistant", "content": "2+2 equals 4."},
      {"role": "user", "content": "And what is that times 10?"}
    ]
  }'

Streaming

Python
JavaScript
cURL

from anthropic import Anthropic

client = Anthropic(
    base_url="https://api.scalellm.dev",
    api_key="sk_your_key"
)

with client.messages.stream(
    model="claude-sonnet-4.5",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Count to 10."}]
) as stream:
    for text in stream.text_stream:
        print(text, end="", flush=True)

import Anthropic from '@anthropic-ai/sdk';

const client = new Anthropic({
  baseURL: 'https://api.scalellm.dev',
  apiKey: 'sk_your_key'
});

const stream = client.messages.stream({
  model: 'claude-sonnet-4.5',
  max_tokens: 1024,
  messages: [{ role: 'user', content: 'Count to 10.' }]
});

for await (const event of stream) {
  if (event.type === 'content_block_delta') {
    process.stdout.write(event.delta.text);
  }
}

curl https://api.scalellm.dev/v1/messages \
  -H "Authorization: Bearer sk_your_key" \
  -H "Content-Type: application/json" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-sonnet-4.5",
    "max_tokens": 1024,
    "stream": true,
    "messages": [
      {"role": "user", "content": "Count to 10."}
    ]
  }'

Streaming returns Server-Sent Events:

event: message_start
data: {"type":"message_start","message":{"id":"msg_01XYZ...","type":"message","role":"assistant",...}}

event: content_block_start
data: {"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":"1"}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":", 2"}}

...

event: message_stop
data: {"type":"message_stop"}

Available Models

Model	Description
`claude-opus-4.5`	Most capable, best for complex tasks
`claude-sonnet-4.5`	Balanced performance and speed
`claude-haiku-4.5`	Fastest, best for simple tasks

Headers

Header	Required	Description
`Authorization`	Yes	`Bearer sk_your_key`
`Content-Type`	Yes	`application/json`
`anthropic-version`	Recommended	API version (e.g., `2023-06-01`)

OpenAI Compatible

Anthropic Compatible

Google Compatible

Reference

Messages

Messages

Endpoint

Examples

Request Body

Message Object

Response

Response Fields

System Prompts

Multi-turn Conversations

Streaming

Available Models

Headers

OpenAI Compatible

Anthropic Compatible

Google Compatible

Reference

​Messages

​Endpoint

​Examples

​Request Body

​Message Object

​Response

​Response Fields

​System Prompts

​Multi-turn Conversations

​Streaming

​Available Models

​Headers

Messages

Endpoint

Examples

Request Body

Message Object

Response

Response Fields

System Prompts

Multi-turn Conversations

Streaming

Available Models

Headers