Customjs MCP for AI Agents

Securely connect your AI agents and chatbots (Claude, ChatGPT, Cursor, etc) with Customjs MCP or direct API to run custom JavaScript automations, generate dynamic PDFs, send transactional emails, and update CRM fields through natural language.

Customjs logoCustomjs
Api Key

Customjs is a code-first automation platform for integrating custom JavaScript logic across your tech stack. It lets you extend applications quickly by writing functions for tasks like emails, PDFs, or CRM updates.

5 Tools

Try Customjs now

Type what you want done — sign in and watch it run live in the Tool Router playground.

TOOL ROUTER PLAYGROUND
Customjs
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TOOLS

Supported Tools

Every Customjs action and event your agent gets out of the box.

Authenticate CustomJS API Key

Authenticate and validate a CustomJS API key.

Convert HTML to PDF

Convert HTML content to a PDF document.

Convert HTML to PNG

Tool to convert HTML string to PNG image.

Merge multiple PDFs into one

Merge multiple PDF files from URLs into a single PDF document.

Run Puppeteer Script

Execute a Puppeteer script in a headless browser and capture a screenshot.

SETUP GUIDE

Connect Customjs MCP Tool with your Agent

1

Install Composio

typescript
npm install @composio/core ai @ai-sdk/openai @ai-sdk/mcp
Install the Composio SDK and Claude Agent SDK
2

Create Tool Router Session

typescript
import { Composio } from '@composio/core';

const composio = new Composio({ apiKey: 'your-api-key' });

console.log("Creating Tool Router session...");
const { mcp } = await composio.create('your-user-id');
console.log(`Tool Router session created: ${mcp.url}`);
Initialize the Composio client and create a Tool Router session
3

Connect to AI Agent

typescript
import { openai } from '@ai-sdk/openai';
import { experimental_createMCPClient as createMCPClient } from '@ai-sdk/mcp';
import { generateText, stepCountIs } from 'ai';

const client = await createMCPClient({
  transport: {
    type: 'http',
    url: mcp.url,
    headers: { 'x-api-key': 'your-composio-api-key' }
  }
});

const tools = await client.tools();

const { text } = await generateText({
  model: openai('gpt-4o'),
  tools,
  messages: [{ role: 'user', content: 'Convert this HTML string to a PDF' }],
  stopWhen: stepCountIs( 5 )
});

console.log(`Agent: ${text}`);
Use the MCP server with your AI agent
SETUP GUIDE

Connect Customjs API Tool with your Agent

1

Install Composio

typescript
npm install @composio/openai
Install the Composio SDK
2

Initialize Composio and Create Tool Router Session

typescript
import OpenAI from 'openai';
import { Composio } from '@composio/core';
import { OpenAIResponsesProvider } from '@composio/openai';

const composio = new Composio({
  provider: new OpenAIResponsesProvider(),
});
const openai = new OpenAI({});
const session = await composio.create('your-user-id');
Import and initialize Composio client, then create a Tool Router session
3

Execute Customjs Tools via Tool Router with Your Agent

typescript
const tools = session.tools;
const response = await openai.responses.create({
  model: 'gpt-4.1',
  tools: tools,
  input: [{
    role: 'user',
    content: 'Convert this HTML invoice to a PDF file.'
  }],
});
const result = await composio.provider.handleToolCalls(
  'your-user-id',
  response.output
);
console.log(result);
Get tools from Tool Router session and execute Customjs actions with your Agent

Why Use Composio?

AI Native Customjs Integration

  • Supports both Customjs MCP and direct API based integrations
  • Structured, LLM-friendly schemas for reliable tool execution
  • Rich coverage for reading, writing, and querying your Customjs data

Managed Auth

  • Built-in OAuth handling with automatic token refresh and rotation
  • Central place to manage, scope, and revoke Customjs access
  • Per user and per environment credentials instead of hard-coded keys

Agent Optimized Design

  • Tools are tuned using real error and success rates to improve reliability over time
  • Comprehensive execution logs so you always know what ran, when, and on whose behalf

Enterprise Grade Security

  • Fine-grained RBAC so you control which agents and users can access Customjs
  • Scoped, least privilege access to Customjs resources
  • Full audit trail of agent actions to support review and compliance
FAQ

Frequently asked questions

Yes, Customjs requires you to configure your own API key credentials. Once set up, Composio handles secure credential storage and API request handling for you.

Yes! Composio's Tool Router enables agents to use multiple toolkits. Learn more.

Composio is SOC 2 and ISO 27001 compliant with all data encrypted in transit and at rest. Learn more.

Composio maintains and updates all toolkit integrations automatically, so your agents always work with the latest API versions.

Start with Customjs.It takes 30 seconds.

Managed auth, hosted MCP servers, and every Customjs tool your agent needs.Free to start.

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