E-Signature API Integration: Best Practices & Code Examples

Integrating e-signatures into your application shouldn't be complicated. Whether you're building a contract management system, HR portal, or custom business application, this guide shows you how to implement bulletproof e-signature workflows.

API Architecture Overview

RESTful Design Principles

Space Sign's API follows REST best practices:

**Base URL:** https://api.spacesign.com/v1

Authentication: Bearer tokens

http

1Authorization: Bearer YOUR_API_KEY

Response Format: JSON

json

1{
2  "status": "success",
3  "data": { ... },
4  "meta": { ... }
5}

Core Integration Workflows

1. Send a Document for Signature

Basic Flow:

Upload document

Define signers

Place signature fields

Send for signing

Code Example (Node.js):

javascript

1const SpaceSign = require('@spacesign/sdk');
2
3const client = new SpaceSign({ apiKey: process.env.SPACESIGN_API_KEY });
4
5async function sendContract() {
6  try {
7    // Step 1: Upload document
8    const document = await client.documents.upload({
9      file: './contract.pdf',
10      title: 'Employment Agreement - John Doe'
11    });
12
13    // Step 2: Add signers
14    const envelope = await client.envelopes.create({
15      documentId: document.id,
16      signers: [
17        {
18          email: 'john.doe@example.com',
19          name: 'John Doe',
20          role: 'Employee',
21          order: 1
22        },
23        {
24          email: 'hr@company.com',
25          name: 'Jane Smith',
26          role: 'HR Manager',
27          order: 2
28        }
29      ]
30    });
31
32    // Step 3: Add signature fields (or use AI auto-tag)
33    await client.envelopes.addFields(envelope.id, {
34      fields: [
35        {
36          type: 'signature',
37          signer: 'john.doe@example.com',
38          page: 1,
39          x: 100,
40          y: 500,
41          width: 200,
42          height: 50
43        },
44        {
45          type: 'date',
46          signer: 'john.doe@example.com',
47          page: 1,
48          x: 100,
49          y: 550
50        }
51      ]
52    });
53
54    // Step 4: Send envelope
55    const sent = await client.envelopes.send(envelope.id, {
56      message: 'Please review and sign your employment agreement.',
57      subject: 'Action Required: Employment Agreement'
58    });
59
60    console.log(`Envelope sent! ID: ${sent.id}`);
61    return sent;
62
63  } catch (error) {
64    console.error('Error sending contract:', error);
65    throw error;
66  }
67}

2. AI-Powered Auto-Tagging

Skip manual field placement - let AI do it:

javascript

1async function sendWithAutoTag() {
2  const document = await client.documents.upload({
3    file: './contract.pdf',
4    title: 'Sales Agreement'
5  });
6
7  // AI automatically detects signature locations
8  const analysis = await client.ai.analyzeDocument(document.id);
9
10  const envelope = await client.envelopes.create({
11    documentId: document.id,
12    signers: [{ email: 'client@example.com', name: 'Client Name' }],
13    autoTag: true  // Magic happens here
14  });
15
16  await client.envelopes.send(envelope.id);
17}

3. Embedded Signing

Integrate signing directly into your app:

javascript

1async function getSigningURL() {
2  const envelope = await client.envelopes.create({ /* ... */ });
3
4  // Generate embedded signing URL
5  const signingSession = await client.envelopes.createSigningSession(
6    envelope.id,
7    {
8      signerEmail: 'john.doe@example.com',
9      returnUrl: 'https://yourapp.com/signing-complete',
10      expiresIn: 3600  // 1 hour
11    }
12  );
13
14  return signingSession.url;
15  // Redirect user to this URL or embed in iframe
16}

Frontend Implementation:

html

1<iframe 
2  src="{{signingUrl}}" 
3  width="100%" 
4  height="600"
5  allow="camera; microphone"
6></iframe>

Webhook Event Handling

Setting Up Webhooks

Register webhook endpoint:

javascript

1await client.webhooks.create({
2  url: 'https://yourapp.com/webhooks/spacesign',
3  events: [
4    'envelope.sent',
5    'envelope.delivered',
6    'envelope.signed',
7    'envelope.completed',
8    'envelope.declined',
9    'envelope.expired'
10  ],
11  secret: 'your-webhook-secret'
12});

Webhook Handler (Express.js)

javascript

1const express = require('express');
2const crypto = require('crypto');
3
4const app = express();
5app.use(express.json());
6
7// Verify webhook signature
8function verifyWebhookSignature(payload, signature, secret) {
9  const hash = crypto
10    .createHmac('sha256', secret)
11    .update(JSON.stringify(payload))
12    .digest('hex');
13  
14  return crypto.timingSafeEqual(
15    Buffer.from(signature),
16    Buffer.from(hash)
17  );
18}
19
20app.post('/webhooks/spacesign', async (req, res) => {
21  const signature = req.headers['x-spacesign-signature'];
22  
23  // Verify authenticity
24  if (!verifyWebhookSignature(req.body, signature, process.env.WEBHOOK_SECRET)) {
25    return res.status(401).send('Invalid signature');
26  }
27
28  const { event, data } = req.body;
29
30  switch (event) {
31    case 'envelope.completed':
32      await handleEnvelopeCompleted(data);
33      break;
34    
35    case 'envelope.signed':
36      await handleEnvelopeSigned(data);
37      break;
38    
39    case 'envelope.declined':
40      await handleEnvelopeDeclined(data);
41      break;
42  }
43
44  res.status(200).send('OK');
45});
46
47async function handleEnvelopeCompleted(data) {
48  console.log(`Envelope ${data.envelopeId} completed!`);
49  
50  // Download signed document
51  const pdf = await client.envelopes.downloadDocument(data.envelopeId);
52  
53  // Update your database
54  await db.contracts.update({
55    id: data.metadata.contractId,
56    status: 'signed',
57    signedDocumentUrl: pdf.url
58  });
59  
60  // Trigger next workflow
61  await triggerOnboarding(data.metadata.employeeId);
62}

Error Handling Best Practices

Implement Retry Logic

javascript

1async function sendWithRetry(envelope, maxRetries = 3) {
2  for (let i = 0; i < maxRetries; i++) {
3    try {
4      return await client.envelopes.send(envelope.id);
5    } catch (error) {
6      if (error.code === 'RATE_LIMIT_EXCEEDED') {
7        // Exponential backoff
8        await sleep(Math.pow(2, i) * 1000);
9        continue;
10      }
11      
12      if (error.code === 'VALIDATION_ERROR') {
13        // Don't retry validation errors
14        throw error;
15      }
16      
17      if (i === maxRetries - 1) throw error;
18    }
19  }
20}

Handle Common Errors

javascript

1try {
2  await client.envelopes.send(envelopeId);
3} catch (error) {
4  switch (error.code) {
5    case 'INVALID_EMAIL':
6      return { error: 'Please check signer email address' };
7    
8    case 'DOCUMENT_NOT_FOUND':
9      return { error: 'Document has been deleted' };
10    
11    case 'INSUFFICIENT_CREDITS':
12      return { error: 'Please upgrade your plan' };
13    
14    case 'RATE_LIMIT_EXCEEDED':
15      return { error: 'Too many requests. Try again in a minute' };
16    
17    default:
18      // Log unexpected errors
19      logger.error('Unexpected API error:', error);
20      return { error: 'Something went wrong. Please try again' };
21  }
22}

Security Best Practices

1. Protect API Keys

NEVER commit API keys to version control:

javascript

1// ❌ BAD
2const client = new SpaceSign({ 
3  apiKey: 'sk_live_abc123...' 
4});
5
6// ✅ GOOD
7const client = new SpaceSign({ 
8  apiKey: process.env.SPACESIGN_API_KEY 
9});

Use different keys for environments:

Development: sk_test_...

Production: sk_live_...

2. Implement Rate Limiting

javascript

1const rateLimit = require('express-rate-limit');
2
3const apiLimiter = rateLimit({
4  windowMs: 60 * 1000, // 1 minute
5  max: 60, // 60 requests per minute
6  message: 'Too many requests from this IP'
7});
8
9app.use('/api/signatures', apiLimiter);

3. Validate Webhook Signatures

Always verify webhooks come from Space Sign:

javascript

1// See webhook handler example above
2if (!verifyWebhookSignature(payload, signature, secret)) {
3  return res.status(401).send('Unauthorized');
4}

4. Use HTTPS Only

javascript

1// Enforce HTTPS in production
2if (process.env.NODE_ENV === 'production') {
3  app.use((req, res, next) => {
4    if (!req.secure) {
5      return res.redirect('https://' + req.headers.host + req.url);
6    }
7    next();
8  });
9}

Performance Optimization

1. Batch Operations

Instead of sending documents one-by-one:

javascript

1// ❌ Slow (sequential)
2for (const employee of employees) {
3  await sendContract(employee);
4}
5
6// ✅ Fast (parallel)
7await Promise.all(
8  employees.map(employee => sendContract(employee))
9);

2. Cache Frequently Accessed Data

javascript

1const NodeCache = require('node-cache');
2const cache = new NodeCache({ stdTTL: 600 }); // 10 minutes
3
4async function getTemplate(id) {
5  const cached = cache.get(`template:${id}`);
6  if (cached) return cached;
7
8  const template = await client.templates.get(id);
9  cache.set(`template:${id}`, template);
10  return template;
11}

3. Use Webhooks Instead of Polling

javascript

1// ❌ BAD: Poll for status
2setInterval(async () => {
3  const status = await client.envelopes.getStatus(envelopeId);
4  if (status === 'completed') {
5    // do something
6  }
7}, 5000);
8
9// ✅ GOOD: Use webhooks
10// Webhook automatically notifies when completed

Testing Your Integration

Unit Tests

javascript

1const nock = require('nock');
2
3describe('SpaceSign Integration', () => {
4  it('should send envelope successfully', async () => {
5    // Mock API response
6    nock('https://api.spacesign.com')
7      .post('/v1/envelopes')
8      .reply(200, {
9        status: 'success',
10        data: { id: 'env_123', status: 'sent' }
11      });
12
13    const result = await sendContract();
14    expect(result.status).toBe('sent');
15  });
16
17  it('should handle rate limit errors', async () => {
18    nock('https://api.spacesign.com')
19      .post('/v1/envelopes')
20      .reply(429, { error: 'Rate limit exceeded' });
21
22    await expect(sendContract()).rejects.toThrow('Rate limit');
23  });
24});

Integration Tests

Use test mode API keys for safe testing:

javascript

1const client = new SpaceSign({ 
2  apiKey: process.env.SPACESIGN_TEST_KEY,
3  testMode: true
4});

Monitoring & Logging

Track API Usage

javascript

1const client = new SpaceSign({ 
2  apiKey: process.env.SPACESIGN_API_KEY,
3  onRequest: (config) => {
4    logger.info('API Request:', {
5      method: config.method,
6      url: config.url,
7      timestamp: new Date()
8    });
9  },
10  onResponse: (response) => {
11    logger.info('API Response:', {
12      status: response.status,
13      duration: response.duration
14    });
15  }
16});

Error Monitoring

Integrate with Sentry or similar:

javascript

1const Sentry = require('@sentry/node');
2
3client.on('error', (error) => {
4  Sentry.captureException(error, {
5    tags: {
6      integration: 'spacesign',
7      endpoint: error.endpoint
8    }
9  });
10});

Conclusion

Building robust e-signature integrations requires:

✅ Proper error handling

✅ Webhook implementation

✅ Security best practices

✅ Performance optimization

✅ Comprehensive testing

Follow these patterns, and you'll have a production-ready integration that scales.

*Need help with your integration? Join our developer community or request technical support.*

E-Signature API Integration: Best Practices & Code Examples

E-Signature API Integration: Best Practices & Code Examples

API Architecture Overview

RESTful Design Principles

Core Integration Workflows

1. Send a Document for Signature

2. AI-Powered Auto-Tagging

3. Embedded Signing

Webhook Event Handling

Setting Up Webhooks

Webhook Handler (Express.js)

Error Handling Best Practices

Implement Retry Logic

Handle Common Errors

Security Best Practices

1. Protect API Keys

2. Implement Rate Limiting

3. Validate Webhook Signatures

4. Use HTTPS Only

Performance Optimization

1. Batch Operations

2. Cache Frequently Accessed Data

3. Use Webhooks Instead of Polling

Testing Your Integration

Unit Tests

Integration Tests

Monitoring & Logging

Track API Usage

Error Monitoring

Conclusion

Ready to Try Space Sign?

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