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Chaindoc SDKs

Chaindoc has two TypeScript SDKs: the Server SDK for backend work (Node.js) and the Embed SDK for dropping a signing UI into your web app. Both have full type definitions, zero runtime dependencies, and work with any framework.

Available SDKs

For npm setup and framework-specific configuration (env variables, providers, etc.), see the installation guide.

  • Server SDK (@chaindoc_io/server-sdk) - Backend integration for Node.js 18+
  • Embed SDK (@chaindoc_io/embed-sdk) - Frontend signing interface for web applications
  • Python SDK - Coming soon
  • PHP SDK - Coming soon

Server SDK

The Server SDK wraps the REST API in a type-safe Node.js interface. You'll use it to manage documents, create signature requests, handle file uploads, and trigger blockchain verification.

Installation

npm install @chaindoc_io/server-sdk

Quick start

server.ts
import { Chaindoc } from '@chaindoc_io/server-sdk';
import { readFile } from 'fs/promises';

// 1. Initialize the SDK
const chaindoc = new Chaindoc({
  secretKey: process.env.CHAINDOC_SECRET_KEY!,
});

// 2. Upload a document file
const buffer = await readFile('./contract.pdf');
const file = new Blob([buffer], { type: 'application/pdf' });
const { media } = await chaindoc.media.upload([file]);

// 3. Create a document
const doc = await chaindoc.documents.create({
  name: 'Service Agreement',
  description: 'Contract for consulting services',
  media: media[0],
  status: 'published', // Triggers blockchain verification
  hashtags: ['#contract', '#2024'],
  meta: [{ key: 'client', value: 'Acme Corp' }],
});

// 4. Create a signature request
const sigRequest = await chaindoc.signatures.createRequest({
  versionId: doc.document.versions[0].uuid,
  recipients: [{ email: 'signer@example.com' }],
  deadline: new Date('2024-12-31'),
  embeddedFlow: true,
});

// 5. Create session for frontend SDK
const session = await chaindoc.embedded.createSession({
  email: 'signer@example.com',
  metadata: {
    documentId: doc.documentId,
    signatureRequestId: sigRequest.signatureRequest.uuid,
  },
});

console.log('Session ID:', session.sessionId);

Express.js Integration

server.ts
import express from 'express';
import { Chaindoc, ChaindocError } from '@chaindoc_io/server-sdk';
import multer from 'multer';

const app = express();
const upload = multer({ storage: multer.memoryStorage() });

const chaindoc = new Chaindoc({
  secretKey: process.env.CHAINDOC_SECRET_KEY!,
});

// Upload and create document
app.post('/api/documents', upload.single('file'), async (req, res) => {
  try {
    const file = new Blob([req.file!.buffer], { type: req.file!.mimetype });
    const { media } = await chaindoc.media.upload([file]);

    const doc = await chaindoc.documents.create({
      name: req.body.name,
      description: req.body.description || '',
      media: media[0],
      status: 'published',
      hashtags: req.body.hashtags || [],
      meta: req.body.meta || [],
    });

    res.json({ documentId: doc.documentId });
  } catch (error) {
    if (error instanceof ChaindocError) {
      res.status(error.statusCode || 500).json({ error: error.message });
    } else {
      res.status(500).json({ error: 'Internal server error' });
    }
  }
});

// Create embedded session for signer
app.post('/api/signing/session', async (req, res) => {
  try {
    const { email, documentId, signatureRequestId } = req.body;

    const session = await chaindoc.embedded.createSession({
      email,
      metadata: { documentId, signatureRequestId },
    });

    res.json({ sessionId: session.sessionId });
  } catch (error) {
    if (error instanceof ChaindocError) {
      res.status(error.statusCode || 500).json({ error: error.message });
    }
  }
});

app.listen(3000);

Next.js API Routes

app/api/signing/create-session/route.ts
import { NextRequest, NextResponse } from 'next/server';
import { Chaindoc, ChaindocError } from '@chaindoc_io/server-sdk';

const chaindoc = new Chaindoc({
  secretKey: process.env.CHAINDOC_SECRET_KEY!,
});

export async function POST(request: NextRequest) {
  try {
    const { email, documentId, signatureRequestId } = await request.json();

    const session = await chaindoc.embedded.createSession({
      email,
      metadata: { documentId, signatureRequestId },
    });

    return NextResponse.json({
      sessionId: session.sessionId,
      expiresAt: session.expiresAt,
    });
  } catch (error) {
    if (error instanceof ChaindocError) {
      return NextResponse.json(
        { error: error.message },
        { status: error.statusCode || 500 }
      );
    }
    return NextResponse.json(
      { error: 'Internal server error' },
      { status: 500 }
    );
  }
}

Error handling

Always wrap API calls in try-catch blocks and handle ChaindocError specifically:

terminal
import { ChaindocError } from '@chaindoc_io/server-sdk';

try {
  const doc = await chaindoc.documents.create({ /* ... */ });
} catch (error) {
  if (error instanceof ChaindocError) {
    console.error('API Error:', error.message);
    console.error('Status Code:', error.statusCode);
    
    switch (error.statusCode) {
      case 400:
        // Bad request - check parameters
        break;
      case 401:
        // Unauthorized - check API key
        break;
      case 404:
        // Not found
        break;
      case 429:
        // Rate limited - SDK will auto-retry
        break;
    }
  }
}

Embed SDK

The Embed SDK lets you show the Chaindoc signing interface inside your web app. It handles the iframe, OTP verification, and communication between your app and Chaindoc. Your users sign documents without leaving your site.

Installation

npm install @chaindoc_io/embed-sdk

Basic usage

terminal
import { ChaindocEmbed } from '@chaindoc_io/embed-sdk';

// 1. Initialize SDK (once per page)
const chaindoc = new ChaindocEmbed({
  publicKey: 'pk_live_xxxxxxxxxxxxx',
  environment: 'production',
});

// 2. Get session from your backend
const response = await fetch('/api/signing/create-session', {
  method: 'POST',
  body: JSON.stringify({ documentId, signerEmail }),
});
const { sessionId } = await response.json();

// 3. Open signing flow
const instance = chaindoc.openSignatureFlow({
  sessionId,
  
  onReady: () => {
    console.log('Signing interface loaded');
  },
  
  onSuccess: (data) => {
    console.log('Document signed:', data.signatureId);
    instance.close();
  },
  
  onError: (error) => {
    console.error('Signing failed:', error.code, error.message);
  },
  
  onCancel: () => {
    console.log('User cancelled');
    instance.close();
  },
});

React integration

components/SignButton.tsx
import { useCallback, useRef, useEffect } from 'react';
import { ChaindocEmbed, EmbedInstance } from '@chaindoc_io/embed-sdk';

function SignButton({ sessionId }: { sessionId: string }) {
  const sdkRef = useRef<ChaindocEmbed | null>(null);
  const instanceRef = useRef<EmbedInstance | null>(null);

  useEffect(() => {
    sdkRef.current = new ChaindocEmbed({
      publicKey: process.env.REACT_APP_CHAINDOC_PUBLIC_KEY!,
    });

    return () => {
      sdkRef.current?.destroy();
    };
  }, []);

  const handleSign = useCallback(() => {
    if (!sdkRef.current) return;

    instanceRef.current = sdkRef.current.openSignatureFlow({
      sessionId,
      onSuccess: (data) => {
        console.log('Signed!', data.signatureId);
        instanceRef.current?.close();
      },
      onCancel: () => {
        instanceRef.current?.close();
      },
    });
  }, [sessionId]);

  return <button onClick={handleSign}>Sign Document</button>;
}

Vue 3 integration

SignButton.vue
<script setup lang="ts">
import { ref, onMounted, onUnmounted } from 'vue';
import { ChaindocEmbed, type EmbedInstance } from '@chaindoc_io/embed-sdk';

const props = defineProps<{ sessionId: string }>();

let sdk: ChaindocEmbed | null = null;
let instance: EmbedInstance | null = null;

onMounted(() => {
  sdk = new ChaindocEmbed({
    publicKey: import.meta.env.VITE_CHAINDOC_PUBLIC_KEY,
  });
});

onUnmounted(() => {
  sdk?.destroy();
});

function openSignature() {
  if (!sdk) return;
  
  instance = sdk.openSignatureFlow({
    sessionId: props.sessionId,
    onSuccess: (data) => {
      console.log('Signed!', data.signatureId);
      instance?.close();
    },
    onCancel: () => {
      instance?.close();
    },
  });
}
</script>

<template>
  <button @click="openSignature">Sign Document</button>
</template>

Inline mode

Instead of a modal, embed the signing interface directly into your page:

terminal
const instance = chaindoc.openSignatureFlow({
  sessionId,
  mode: 'inline',
  container: document.getElementById('signature-container'),
  
  onSuccess: (data) => {
    console.log('Signed!');
  },
});

Theming

Customize the appearance with light or dark themes:

terminal
const instance = chaindoc.openSignatureFlow({
  sessionId,
  theme: 'dark',
  // ... other options
});

// Change theme dynamically
instance.changeTheme('light');

Full workflow example

This puts both SDKs together: Server SDK on the backend to create documents and sessions, Embed SDK on the frontend to show the signing UI.

1Backend: Upload DocumentUse Server SDK to upload file and create document

2Backend: Create Signature RequestCreate signature request with embedded flow enabled

3Backend: Generate SessionCreate embedded session for each signer

4Frontend: Initialize Embed SDKInitialize SDK with public key

5Frontend: Open Signing FlowOpen signing interface with session ID

6Frontend: Handle SuccessProcess signed document and update UI

// server.ts
import { Chaindoc } from '@chaindoc_io/server-sdk';

const chaindoc = new Chaindoc({
  secretKey: process.env.CHAINDOC_SECRET_KEY!,
});

// Upload & create document
const { media } = await chaindoc.media.upload([pdfFile]);
const doc = await chaindoc.documents.create({
  name: 'Contract',
  description: 'Service agreement',
  media: media[0],
  status: 'published',
  hashtags: ['#contract'],
  meta: [],
});

// Create signature request
const sigRequest = await chaindoc.signatures.createRequest({
  versionId: doc.document.versions[0].uuid,
  recipients: [{ email: 'signer@example.com' }],
  deadline: new Date('2024-12-31'),
  embeddedFlow: true,
});

// Create session
const session = await chaindoc.embedded.createSession({
  email: 'signer@example.com',
  metadata: {
    documentId: doc.documentId,
    signatureRequestId: sigRequest.signatureRequest.uuid,
  },
});

// Return sessionId to frontend
res.json({ sessionId: session.sessionId });

Best practices

  • Initialize SDK once per page/component lifecycle
  • Always destroy SDK instance on component unmount
  • Handle all callback events (onSuccess, onError, onCancel)
  • Store API keys in environment variables
  • Use TypeScript for better type safety
  • Implement proper error handling with ChaindocError
  • Test with sandbox keys before production deployment

Environment configuration

// Backend
const chaindoc = new Chaindoc({
  secretKey: 'sk_live_xxxxx',
});

// Frontend
const embed = new ChaindocEmbed({
  publicKey: 'pk_live_xxxxx',
  environment: 'production',
});

What to do next

  • Installation — npm setup, env config, and framework-specific providers
  • API documentation — full REST endpoint reference
  • Webhooks — real-time event notifications for your backend
  • Quick start — send your first signature in 10 minutes
  • Security — API key management and production hardening