OpenClaw API Integration Guide: Building Custom AI Workflows

OpenClaw provides a powerful API that allows developers to integrate AI assistant capabilities directly into their applications. Whether you're building custom dashboards, automating business processes, or creating entirely new AI-powered products, the OpenClaw API gives you the tools to make it happen.

This comprehensive guide covers everything you need to know about integrating with OpenClaw programmatically, from basic REST endpoints to advanced webhook configurations and real-time event streaming.

Understanding the OpenClaw API Architecture

The OpenClaw API follows REST principles while incorporating WebSocket connections for real-time communication. This hybrid approach allows for both synchronous request-response patterns and asynchronous event-driven workflows.

Core Components

The API is organized around several key resources:

Sessions represent individual conversation threads with the AI assistant. Each session maintains its own context, memory, and state. Sessions can be created, queried, and managed through dedicated endpoints.

Messages are the fundamental unit of communication. You can send messages to sessions and receive AI responses. Messages support various content types including text, files, and structured data.

Tools extend the assistant's capabilities. The API allows you to register custom tools, configure built-in tools, and manage tool permissions on a per-session basis.

Events provide real-time updates about session activity. Through WebSocket connections or webhook callbacks, you can receive notifications about message completions, tool executions, and status changes.

Authentication and Authorization

OpenClaw uses API keys for authentication. Each key is associated with an account and can be scoped to specific permissions.

Generating API Keys

To create an API key, access your OpenClaw dashboard and navigate to the API section. You can generate keys with different permission levels:

Read-only keys can query sessions and messages but cannot initiate new conversations
Standard keys have full access to create sessions and send messages
Admin keys can manage account settings and create additional keys

Using API Keys

Include your API key in the Authorization header of every request:

curl -H "Authorization: Bearer oclaw_live_your_key_here" \
     -H "Content-Type: application/json" \
     https://api.openclaw.com/v1/sessions

For client-side applications, consider using short-lived tokens generated from your backend to avoid exposing your main API key.

Session Management

Sessions are the foundation of all interactions with OpenClaw. Each session represents a distinct conversation thread with full context preservation.

Creating Sessions

To start a new conversation, create a session with your desired configuration:

const response = await fetch('https://api.openclaw.com/v1/sessions', {
  method: 'POST',
  headers: {
    'Authorization': `Bearer ${apiKey}`,
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    model: 'claude-sonnet-4-20250514',
    system_prompt: 'You are a helpful customer service assistant.',
    tools: ['web_search', 'calculator'],
    metadata: {
      customer_id: 'cust_12345',
      department: 'support'
    }
  })
});

const session = await response.json();
console.log('Session created:', session.id);

The response includes the session ID, which you'll use for all subsequent interactions:

{
  "id": "sess_abc123def456",
  "model": "claude-sonnet-4-20250514",
  "created_at": "2026-02-20T10:30:00Z",
  "status": "active",
  "tools": ["web_search", "calculator"],
  "metadata": {
    "customer_id": "cust_12345",
    "department": "support"
  }
}

Session Configuration Options

When creating sessions, you can customize numerous parameters:

Model selection determines which Claude model powers the session. Options include claude-sonnet-4-20250514 for most use cases, claude-opus-4-20250514 for complex reasoning, and claude-haiku for fast, lightweight tasks.

System prompts define the assistant's personality and behavior. You can include detailed instructions, context about your application, and behavioral guidelines.

Tool configuration specifies which capabilities are available. You can enable built-in tools like web search and file handling, or register custom tools specific to your application.

Memory settings control how the session handles context. Options include automatic summarization for long conversations, explicit memory files, and external knowledge base integration.

Retrieving Session State

Query existing sessions to check their status and retrieve conversation history:

const session = await fetch(
  `https://api.openclaw.com/v1/sessions/${sessionId}`,
  { headers: { 'Authorization': `Bearer ${apiKey}` } }
).then(r => r.json());

console.log('Messages:', session.messages.length);
console.log('Tokens used:', session.token_count);

Listing Sessions

Retrieve all sessions for your account with optional filtering:

const sessions = await fetch(
  'https://api.openclaw.com/v1/sessions?status=active&limit=50',
  { headers: { 'Authorization': `Bearer ${apiKey}` } }
).then(r => r.json());

Filter options include status (active, completed, archived), date ranges, metadata values, and model type.

Sending Messages

Once you have a session, you can send messages and receive AI responses.

Basic Message Sending

The simplest interaction is sending a text message:

const response = await fetch(
  `https://api.openclaw.com/v1/sessions/${sessionId}/messages`,
  {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${apiKey}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      content: 'What are the key features of your product?'
    })
  }
);

const message = await response.json();
console.log('AI Response:', message.content);

Streaming Responses

For real-time response display, use streaming mode:

const response = await fetch(
  `https://api.openclaw.com/v1/sessions/${sessionId}/messages`,
  {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${apiKey}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      content: 'Explain quantum computing in detail.',
      stream: true
    })
  }
);

const reader = response.body.getReader();
const decoder = new TextDecoder();

while (true) {
  const { done, value } = await reader.read();
  if (done) break;
  
  const chunk = decoder.decode(value);
  const lines = chunk.split('\n').filter(line => line.startsWith('data: '));
  
  for (const line of lines) {
    const data = JSON.parse(line.slice(6));
    if (data.type === 'content_delta') {
      process.stdout.write(data.text);
    }
  }
}

Attaching Files

Send files along with messages for the AI to analyze:

const formData = new FormData();
formData.append('content', 'Please analyze this spreadsheet.');
formData.append('files', fileBlob, 'data.csv');

const response = await fetch(
  `https://api.openclaw.com/v1/sessions/${sessionId}/messages`,
  {
    method: 'POST',
    headers: { 'Authorization': `Bearer ${apiKey}` },
    body: formData
  }
);

Supported file types include documents (PDF, DOCX, TXT), images (PNG, JPEG, WebP), spreadsheets (CSV, XLSX), and code files in various languages.

Tool Integration

Tools extend what OpenClaw can do within your sessions. You can use built-in tools or create custom ones.

Built-in Tools

OpenClaw includes several built-in tools:

web_search: Search the internet for current information
web_fetch: Retrieve and parse web page content
calculator: Perform mathematical calculations
code_interpreter: Execute Python code safely
file_handler: Read, write, and manipulate files

Enable tools when creating a session:

const session = await createSession({
  model: 'claude-sonnet-4-20250514',
  tools: ['web_search', 'calculator', 'code_interpreter']
});

Creating Custom Tools

Define custom tools that connect to your own APIs and services:

const customTool = {
  name: 'get_customer_orders',
  description: 'Retrieves order history for a customer',
  parameters: {
    type: 'object',
    properties: {
      customer_id: {
        type: 'string',
        description: 'The unique customer identifier'
      },
      limit: {
        type: 'integer',
        description: 'Maximum number of orders to return',
        default: 10
      }
    },
    required: ['customer_id']
  }
};

// Register the tool with your session
await fetch(`https://api.openclaw.com/v1/sessions/${sessionId}/tools`, {
  method: 'POST',
  headers: {
    'Authorization': `Bearer ${apiKey}`,
    'Content-Type': 'application/json'
  },
  body: JSON.stringify(customTool)
});

Handling Tool Calls

When the AI decides to use a tool, you'll receive a tool call event. For custom tools, you need to execute the logic and return the result:

// When you receive a tool_call event
const toolCall = event.tool_call;

if (toolCall.name === 'get_customer_orders') {
  const orders = await yourDatabase.getOrders(
    toolCall.parameters.customer_id,
    toolCall.parameters.limit
  );
  
  // Submit the result back to OpenClaw
  await fetch(
    `https://api.openclaw.com/v1/sessions/${sessionId}/tool-results`,
    {
      method: 'POST',
      headers: {
        'Authorization': `Bearer ${apiKey}`,
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({
        tool_call_id: toolCall.id,
        result: JSON.stringify(orders)
      })
    }
  );
}

Webhooks and Events

Webhooks allow you to receive real-time notifications about session activity without maintaining persistent connections.

Configuring Webhooks

Set up a webhook endpoint in your OpenClaw dashboard or via API:

await fetch('https://api.openclaw.com/v1/webhooks', {
  method: 'POST',
  headers: {
    'Authorization': `Bearer ${apiKey}`,
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    url: 'https://your-app.com/webhooks/openclaw',
    events: ['message.completed', 'tool.called', 'session.ended'],
    secret: 'your_webhook_secret'
  })
});

Webhook Event Types

OpenClaw sends various event types:

message.created: A new message was added to a session
message.completed: The AI finished generating a response
tool.called: The AI invoked a tool
tool.completed: A tool execution finished
session.created: A new session was started
session.ended: A session was closed or expired
error.occurred: An error happened during processing

Verifying Webhook Signatures

Always verify webhook signatures to ensure authenticity:

const crypto = require('crypto');

function verifyWebhook(payload, signature, secret) {
  const expectedSignature = crypto
    .createHmac('sha256', secret)
    .update(payload)
    .digest('hex');
  
  return crypto.timingSafeEqual(
    Buffer.from(signature),
    Buffer.from(expectedSignature)
  );
}

// In your webhook handler
app.post('/webhooks/openclaw', (req, res) => {
  const signature = req.headers['x-openclaw-signature'];
  const payload = JSON.stringify(req.body);
  
  if (!verifyWebhook(payload, signature, webhookSecret)) {
    return res.status(401).send('Invalid signature');
  }
  
  // Process the event
  const event = req.body;
  console.log('Received event:', event.type);
  
  res.status(200).send('OK');
});

WebSocket Connections

For applications requiring real-time bidirectional communication, use WebSocket connections.

Establishing Connections

Connect to the WebSocket endpoint with your session ID:

const ws = new WebSocket(
  `wss://api.openclaw.com/v1/sessions/${sessionId}/ws`,
  { headers: { 'Authorization': `Bearer ${apiKey}` } }
);

ws.on('open', () => {
  console.log('Connected to session');
});

ws.on('message', (data) => {
  const event = JSON.parse(data);
  handleEvent(event);
});

ws.on('close', () => {
  console.log('Connection closed');
});

Sending Messages via WebSocket

Once connected, send messages directly through the WebSocket:

ws.send(JSON.stringify({
  type: 'message',
  content: 'Hello, can you help me with something?'
}));

Handling Real-time Events

Process events as they arrive:

function handleEvent(event) {
  switch (event.type) {
    case 'content_start':
      console.log('AI started responding');
      break;
    case 'content_delta':
      process.stdout.write(event.text);
      break;
    case 'content_end':
      console.log('\nResponse complete');
      break;
    case 'tool_call':
      handleToolCall(event.tool_call);
      break;
    case 'error':
      console.error('Error:', event.message);
      break;
  }
}

Rate Limits and Best Practices

Understanding rate limits helps you build reliable integrations.

Rate Limit Headers

Every API response includes rate limit information:

X-RateLimit-Limit: 1000
X-RateLimit-Remaining: 999
X-RateLimit-Reset: 1708423200

Handling Rate Limits

Implement exponential backoff when you hit rate limits:

async function apiCallWithRetry(fn, maxRetries = 3) {
  for (let i = 0; i < maxRetries; i++) {
    try {
      return await fn();
    } catch (error) {
      if (error.status === 429) {
        const retryAfter = error.headers['retry-after'] || Math.pow(2, i);
        console.log(`Rate limited, retrying in ${retryAfter}s`);
        await sleep(retryAfter * 1000);
      } else {
        throw error;
      }
    }
  }
  throw new Error('Max retries exceeded');
}

Optimization Tips

To maximize efficiency and minimize costs:

Batch operations when possible instead of making many small requests
Use streaming for long responses to improve perceived performance
Cache session data locally to reduce API calls
Implement connection pooling for WebSocket connections
Monitor token usage and optimize prompts to reduce costs

Error Handling

The API uses standard HTTP status codes and provides detailed error messages.

Error Response Format

{
  "error": {
    "code": "invalid_request",
    "message": "The 'model' field is required",
    "param": "model",
    "type": "validation_error"
  }
}

Common Error Codes

400 Bad Request: Invalid parameters or malformed request
401 Unauthorized: Invalid or missing API key
403 Forbidden: Insufficient permissions
404 Not Found: Resource doesn't exist
429 Too Many Requests: Rate limit exceeded
500 Internal Server Error: Something went wrong on our end

Implementing Error Handling

async function safeApiCall(fn) {
  try {
    return await fn();
  } catch (error) {
    if (error.status === 401) {
      // Re-authenticate
      await refreshApiKey();
      return fn();
    } else if (error.status === 404) {
      // Session may have expired, create new one
      return createNewSession();
    } else if (error.status >= 500) {
      // Server error, retry with backoff
      return apiCallWithRetry(fn);
    }
    throw error;
  }
}

SDK Libraries

OpenClaw provides official SDKs for popular languages:

Node.js SDK

npm install @openclaw/sdk

import { OpenClaw } from '@openclaw/sdk';

const client = new OpenClaw({ apiKey: process.env.OPENCLAW_API_KEY });

const session = await client.sessions.create({
  model: 'claude-sonnet-4-20250514',
  systemPrompt: 'You are a helpful assistant.'
});

const response = await session.send('Hello!');
console.log(response.content);

Python SDK

pip install openclaw

from openclaw import OpenClaw

client = OpenClaw(api_key=os.environ["OPENCLAW_API_KEY"])

session = client.sessions.create(
    model="claude-sonnet-4-20250514",
    system_prompt="You are a helpful assistant."
)

response = session.send("Hello!")
print(response.content)

Conclusion

The OpenClaw API provides a robust foundation for building AI-powered applications. From simple chatbots to complex autonomous agents, the API's flexibility allows you to create exactly what you need.

Key takeaways:

Sessions maintain conversation context and state
Messages support text, files, and streaming
Tools extend capabilities with built-in and custom functions
Webhooks and WebSockets enable real-time integrations
SDKs simplify development in popular languages

Start experimenting with the API today and discover how OpenClaw can transform your applications. For additional resources, check out our developer documentation, API reference, and community examples.