WordPress API integration is connecting your WordPress site to external services through their REST or GraphQL APIs so data flows automatically between systems — without manual export/import or copy-paste. I build integrations for payment processing (Stripe, PayPal), accounting (Xero, MYOB, QuickBooks), shipping (Australia Post eParcel PAC API, Royal Mail OBA API, UPS, FedEx), booking (FareHarbor, Rezgo), CRM (HubSpot, Salesforce), and custom internal APIs. Every integration includes authentication handling, error logging, and rate-limit retry logic.
Who it's for
What's included
How the process works
Discovery
We confirm the API, the exact data you need to move, how often (real-time webhook vs scheduled sync), and authentication method (OAuth 2.0, API key, JWT). I review the API documentation and flag any rate limits or sandbox restrictions before scoping.
Build & connect
I build the integration in a WordPress plugin using proper hooks and the WordPress HTTP API — not hardcoded cURL calls — with sandbox/test-mode credentials, complete error handling and logging from day one.
Test edge cases
I test API failures, rate-limit responses (HTTP 429), expired tokens, empty response bodies, and network timeouts to confirm the integration degrades gracefully and retries correctly rather than silently losing data.
Deploy & document
I deploy to production, monitor the first live runs, and hand over documentation covering the API credentials, webhook endpoints, the schedule for any cron-based syncs, and how to check the error log.
Common questions
If a service offers a documented REST or GraphQL API, I can almost always build a WordPress integration for it — even when no WordPress plugin for that service exists. I've built integrations for Stripe, Xero, MYOB, Salesforce, HubSpot, Mailchimp, Klaviyo, Australia Post eParcel, Royal Mail OBA, FareHarbor, Twilio SMS, Intercom, Pipedrive, and custom internal ERP and inventory management APIs. The feasibility question is rarely 'can this be done' and usually 'what's the correct data model and sync frequency'. Tell me the service and what you want to happen — I'll confirm feasibility and give you a fixed-price quote before any work starts.
Yes. I build every integration as a standalone WordPress plugin using proper WordPress hooks (action hooks and filter hooks), the WordPress HTTP API for all outbound requests, and WordPress transients for caching API responses — not inline code in theme functions.php that gets wiped on theme updates. The integration plugin is independent of the active theme and survives core, theme and other plugin updates without modification. I also add the integration to a WordPress must-use plugin (mu-plugin) directory where appropriate, so it can't be accidentally deactivated from the plugins admin screen.
Yes. I build both directional flows: outbound (WordPress pushes data to the external service on form submission, WooCommerce order, or scheduled cron) and inbound (external service pushes data to a WordPress REST endpoint via webhook). For inbound webhooks, I implement webhook signature verification (HMAC-SHA256 for Stripe webhooks, for example) and idempotency key checks to ensure each event is processed exactly once — even if the service retries delivery. For CRM integrations specifically, two-way sync between WordPress forms and HubSpot or Salesforce is a common and well-tested integration pattern.
The integration handles this gracefully rather than failing silently. I implement exponential backoff retry logic (attempts at 1s, 2s, 4s, 8s intervals up to a configurable maximum) for transient failures and HTTP 503 responses. Rate-limit responses (HTTP 429) trigger a backoff based on the Retry-After header the API returns. All failed API calls are logged to a custom WordPress error log table with the request payload, response code, and timestamp — and an admin email alert fires if the failure count exceeds a threshold. This means you know about integration problems before they become data-loss events.
Yes. Accounting system integrations are one of the most common API requests for WooCommerce stores and professional services WordPress sites. For Xero, I use the Xero API v2 OAuth 2.0 connection to sync: WooCommerce orders to Xero invoices (with correct GST/VAT tax code mapping); WooCommerce customers to Xero contacts; and refunds to Xero credit notes. For MYOB AccountRight, I use the MYOB API v2. For QuickBooks Online, I use the Intuit OAuth 2.0 API. All three support both real-time sync on WooCommerce order completion and scheduled batch sync for high-volume stores. If you also need CRM-to-accounting data flows, see my CRM integration service — some businesses need all three systems (WordPress, CRM, accounting) to talk to each other simultaneously.