Almost every modern business application relies on APIs Application Programming Interfaces. Your payment gateway, communication tools, CRM, shipping provider and marketing platform all connect through APIs. When these connections work well, your business runs smoothly and automatically. When they break or are poorly implemented, things fall apart. Hiring the right API developer from the start saves months of rework.
What API integration means in practice: An API developer writes code that reads from or writes to a third-party service Stripe, Twilio, Salesforce, HubSpot, FedEx, or any other platform that exposes an API. The developer handles authentication, error handling, retries, webhooks and data mapping between systems.
Common API Integrations Businesses Need
- Payment APIs - Stripe, PayPal, Braintree: charge cards, handle subscriptions, process refunds
- Communication APIs - Twilio: SMS, voice calls, WhatsApp, video; SendGrid: transactional email
- CRM APIs - HubSpot, Salesforce, Zoho: sync contacts, deals and activities from your application
- Shipping and logistics - FedEx, UPS, Royal Mail: generate labels, track parcels, calculate rates
- Google APIs - Maps, Calendar, Drive, Sheets: location features, scheduling, document management
- Social login - Google, Facebook, Apple OAuth: let users sign in with existing accounts
- Accounting - QuickBooks, Xero: sync invoices, expenses and payments automatically
- eCommerce platforms - Shopify, WooCommerce APIs: sync inventory, orders and customers with third-party tools
What Good API Integration Looks Like
Copying a cURL example from a documentation page is not API integration. Professional API integration includes:
- Authentication - Secure storage of API keys and OAuth tokens (never in source code)
- Error handling - Graceful handling of 429 rate limits, 500 server errors and network timeouts
- Retry logic - Automatic retries with exponential backoff for transient failures
- Webhook handling - Verified, idempotent webhook endpoints that process events reliably
- Logging and monitoring - Full request/response logging for debugging and auditing
- Data mapping - Clean transformation between your data model and the external API's format
Webhooks The Harder Part
Many API integrations fail because of poor webhook handling. A webhook is a POST request that the external service sends to your server when something happens a payment is successful, a call ends, a message is delivered. Your server must respond within a few seconds, verify the signature, process the event idempotently (no duplicate processing if the webhook fires twice) and handle queuing for slow operations. This is where junior developers commonly make mistakes that cause data inconsistencies in production.
API Integrations I Specialise In
- Twilio - Voice, SMS, WhatsApp, Video and Verify APIs. Built 20+ Twilio integrations.
- Stripe - Payments, subscriptions, invoicing, Connect for marketplace payments
- WordPress REST API - Headless WordPress, custom endpoints, third-party integrations
- Google APIs - Calendar, Maps, Drive, Sheets, OAuth
- HubSpot and Salesforce - CRM sync from web applications and eCommerce stores
- Magento / WooCommerce APIs - Order management, inventory sync, fulfilment automation
How to Find the Right API Developer
- Ask specifically about the API you need integrated not just "have you done API work?"
- Look for evidence of webhook handling in their portfolio (most junior developers skip this)
- Check their reviews for phrases like "handled edge cases well" or "dealt with issues professionally" - these indicate production API experience
- Ask: "How do you handle API rate limits in production?" - the answer reveals their experience level immediately