JavaScript SDK Quick Start¶

Get started with the eSign JavaScript SDK in 5 minutes.

Overview¶

The eSign JavaScript SDK is a client library for integrating digital document signing into your web applications. It works in both Browser and Node.js environments.

Feature	Supported
Browser	Yes
Node.js	Yes
TypeScript	Yes
Zero Dependencies	Yes (browser)

Installation¶

Browser (CDN/Local)¶

<!-- Development -->
<script src="dist/esign-sdk.js"></script>

<!-- Production (minified) -->
<script src="dist/esign-sdk.min.js"></script>

Quick Start¶

Step 1: Include the SDK¶

BrowserNode.js

<script src="esign-sdk.min.js"></script>
<script>
    const { ESignClient, ESignRequest, ESignMode } = ESignSDK;
</script>

const { ESignClient, ESignRequest, ESignMode } = require('./esign-sdk.min.js');

Step 2: Initialize Client¶

const client = new ESignClient({
    apiBaseUrl: 'https://your-api-server.com',  // Your eSign API server
    token: 'your-api-token',                     // Token from Capricorn
    key: 'your-api-key'                          // Key from Capricorn
});

Step 3: Sign Document¶

// Create signing request
const response = await client.signDocument(
    new ESignRequest()
        .pdf64(base64EncodedPdf)      // Base64 PDF
        .title('Contract Agreement')   // Document title
        .mode(ESignMode.OTP)          // Authentication mode
        .signerName('John Doe')        // Signer name
);

// Redirect user to authentication page
window.open(response.redirectUrl, '_blank');

// Store reference for later
const reference = response.reference;

Step 4: Download Signed PDF¶

// After user completes OTP authentication...
const signedPdf = await client.downloadSignedDocumentBlob(reference);

// Save file
ESignUtils.downloadBlob(signedPdf, 'signed_document.pdf');

Authentication Modes¶

Mode	Code	Description
OTP	`ESignMode.OTP`	OTP to registered mobile
Biometric	`ESignMode.BIO`	Fingerprint scan
Iris	`ESignMode.IRIS`	Iris scan
Face	`ESignMode.FACE`	Face recognition
eKYC	`ESignMode.CAPRICORN_EKYC`	Pre-verified KYC (requires `ekycId`)

Complete Browser Example¶

<!DOCTYPE html>
<html>
<head>
    <title>eSign Demo</title>
</head>
<body>
    <input type="file" id="pdfFile" accept=".pdf">
    <input type="text" id="signerName" placeholder="Your Name">
    <button onclick="signDocument()">Sign Document</button>

    <script src="esign-sdk.min.js"></script>
    <script>
    const { ESignClient, ESignRequest, ESignMode, ESignUtils } = ESignSDK;

    const client = new ESignClient({
        apiBaseUrl: 'https://your-api-server.com',
        token: 'your-token',
        key: 'your-key'
    });

    async function signDocument() {
        // Get file and convert to Base64
        const file = document.getElementById('pdfFile').files[0];
        const pdf64 = await ESignUtils.fileToBase64(file);
        const signerName = document.getElementById('signerName').value;

        // Sign document
        const response = await client.signDocument(
            new ESignRequest()
                .pdf64(pdf64)
                .title(file.name)
                .mode(ESignMode.OTP)
                .signerName(signerName)
        );

        // Redirect to OTP page
        window.open(response.redirectUrl, '_blank');

        // Store reference
        localStorage.setItem('esign_ref', response.reference);
    }
    </script>
</body>
</html>

Common Issues¶

Issue	Solution
CORS error	Ensure your API server has CORS enabled
Network error	Check API URL and server availability
Invalid PDF	Verify Base64 encoding is correct
Missing ekycId	Add `.ekycId('...')` for eKYC mode

Next Steps¶

Complete JavaScript SDK Guide - Full API reference
eSign API Guide - Backend API documentation
API Reference Card - Quick reference

Server Required

The JavaScript SDK is a client library. You must have the eSign API server running. See Deployment Checklist for server setup.