API Integration Best Practices

Professional API Integration Best Practices

Master REST API integration with production-ready patterns for authentication, error handling, rate limiting, webhooks, retries, and security. Build reliable integrations that scale.

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Quick Answer

Professional API integration requires following production-grade patterns: use API keys with proper secret management, implement exponential backoff retries for transient failures, handle rate limits gracefully, validate webhooks with signature verification, log all requests/responses for debugging, and implement circuit breakers for failing dependencies. Always use idempotency keys for critical operations, handle errors at multiple levels (network, HTTP status, API errors), and test edge cases including timeouts, malformed responses, and partial failures.

Integration Time

2-5 days

Security Level

Production

Reliability

99.9%+

Authentication & Security Best Practices

Secure API Key Management

Never hardcode keys, use environment variables and secret managers

API keys are credentials that grant access to external services. Treat them like passwords—never commit them to version control, hardcode them in source code, or expose them in client-side JavaScript.

❌ NEVER do this:

// Hardcoded API key - SECURITY VULNERABILITY!

const apiKey = 'sk_live_abc123...'; // DON'T DO THIS

✅ Instead, use environment variables:

// .env file (never commit this file)

TURBODOCX_API_KEY=sk_live_abc123...

// In your code

const apiKey = process.env.TURBODOCX_API_KEY;

🔐 Production Secret Management

For production environments, use dedicated secret managers:

• AWS Secrets Manager: Encrypted storage with automatic rotation
• HashiCorp Vault: Self-hosted secrets management with audit logging
• Azure Key Vault: Cloud-based key and secret management
• Google Secret Manager: Secure storage for API keys and credentials

Always Use HTTPS/TLS

Encrypt all API traffic to prevent man-in-the-middle attacks

Every API request must use HTTPS (not HTTP) to encrypt data in transit. This protects API keys, sensitive payload data, and user information from being intercepted.

// Verify HTTPS in your requests

const apiUrl = 'https://api.turbodocx.com/v1'; // ✓ Secure

// const apiUrl = 'http://api.turbodocx.com/v1'; // ✗ INSECURE

Verify Webhook Signatures

Authenticate webhook requests to prevent spoofing attacks

Webhooks are HTTP callbacks sent from the API to your server when events occur. Always verify webhook signatures to ensure requests actually came from the API provider and weren't forged by attackers.

// Example: Verify TurboDocx webhook signature

import crypto from 'crypto';

function verifyWebhook(payload, signature, secret) {

const hmac = crypto.createHmac('sha256', secret);

const digest = hmac.update(payload).digest('hex');

return crypto.timingSafeEqual(

Buffer.from(signature),

Buffer.from(digest)

);

}

⚠️ Security Risk

Without signature verification, attackers can send fake webhook events to your server, potentially triggering unauthorized actions like marking invoices as paid or releasing deliverables.

Error Handling & Retry Strategies

APIs fail. Networks timeout. Services go down. Production-grade integrations handle errors gracefully at multiple levels: network failures, HTTP errors, and API-specific error responses.

Exponential Backoff Retries

For transient failures (network timeouts, 500 errors, rate limits), retry the request with exponential backoff. Start with 1 second delay, then 2s, 4s, 8s, etc. This prevents overwhelming already-struggling services.

// Exponential backoff retry implementation

async function retryWithBackoff(fn, maxRetries = 3) {

for (let i = 0; i < maxRetries; i++) {

try {

return await fn();

} catch (error) {

if (i === maxRetries - 1) throw error;

const delay = Math.pow(2, i) * 1000; // 1s, 2s, 4s

await new Promise(resolve => setTimeout(resolve, delay));

}

💡 When to Retry vs Fail Fast

Retry: 500/502/503/504 errors, network timeouts, rate limits (429)

Fail immediately: 400 (bad request), 401 (unauthorized), 404 (not found), 422 (validation error)

Handle Rate Limits Gracefully

Most APIs enforce rate limits (e.g., 100 requests per minute). When you hit the limit, the API returns a 429 status. Respect this by backing off and retrying after the specified delay.

// Handle 429 rate limit responses

if (response.status === 429) {

const retryAfter = response.headers.get('Retry-After');

const delay = retryAfter ? parseInt(retryAfter) * 1000 : 60000;

await new Promise(r => setTimeout(r, delay));

return retryRequest();

}

Implement Circuit Breakers

If an API is consistently failing (e.g., 10 failures in a row), stop making requests for a cooldown period. This prevents cascading failures and gives the service time to recover.

🔧 Circuit Breaker Pattern

After 10 consecutive failures, enter "open" state (reject all requests immediately). After 1 minute cooldown, enter "half-open" state (allow one test request). If it succeeds, return to "closed" (normal operation). If it fails, remain open for another cooldown period.

Webhook Best Practices

Webhooks enable real-time event notifications from APIs. Instead of polling for updates every minute, webhooks push events to your server instantly when they occur.

Respond Quickly (< 5s)

Webhook endpoints should respond with 200 OK within 5 seconds. Don't do heavy processing inline—acknowledge receipt immediately, then process asynchronously in a background job.

// Good: Quick response + async processing

app.post('/webhooks', (req, res) => {

queue.add('process-webhook', req.body);

res.json({success: true});

});

Handle Duplicate Events

APIs may send the same webhook event multiple times (retries on timeout). Use idempotency keys or event IDs to detect and ignore duplicate events.

// Check for duplicate events

const eventId = req.body.id;

const exists = await db.webhooks.exists(eventId);

if (exists) return res.json({ok: true});

await db.webhooks.insert(eventId);

Webhook Security Checklist

Verify signatures: Always validate HMAC signatures before processing
Use HTTPS endpoints: Webhook URLs must be https:// not http://
Check timestamp: Reject events older than 5 minutes to prevent replay attacks
IP allowlisting (optional): Restrict webhook endpoints to known API provider IPs

Testing API Integrations

Untested API integrations fail in production. Test not just the happy path, but also edge cases: network failures, malformed responses, rate limits, and partial data.

Use Sandbox/Test Environments

Most APIs provide separate test environments with dummy data. Use these for development and CI/CD testing. Never test against production APIs—you might accidentally charge customers or send real emails.

✅ Testing Best Practices

• Use test API keys (often prefixed with test_ or sk_test_)
• Test with sandbox data that won't affect production systems
• Automate tests in CI/CD pipelines
• Test error scenarios (network failures, invalid data, timeouts)

Mock External APIs in Unit Tests

For fast unit tests, mock external API calls instead of making real HTTP requests. This makes tests faster, more reliable, and independent of API availability.

// Example: Mock API responses with Jest

jest.mock('@turbodocx/sdk');

test('creates document', async () => {

TurboDocx.generateDocument.mockResolvedValue({

id: 'doc_123',

status: 'completed'

});

const result = await createDocument();

expect(result.id).toBe('doc_123');

});

Monitoring & Logging

Production API integrations require observability. Log all requests and responses, monitor error rates, and set up alerts for failures.

What to Log

Request details: HTTP method, URL, headers (excluding auth tokens), request body
Response details: Status code, response body, response time
Errors: Full error messages, stack traces, retry attempts
Context: User ID, request ID, correlation ID for tracing

⚠️ Privacy & PCI Compliance

Never log sensitive data: API keys, passwords, credit card numbers, PII (emails, phone numbers), or authentication tokens. Redact these fields before logging.

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