Hire JSON API Developers

JSON (JavaScript Object Notation) is the standard data format for web API communication. The WordPress REST API – built into WordPress core – exposes WordPress content and functionality as JSON endpoints. This allows external applications, JavaScript front ends, and mobile apps to read and write WordPress data using standard HTTP requests.

JSON API work in WordPress covers two directions. The first is consuming external APIs from WordPress – a plugin or custom code that fetches JSON data from a third-party service (weather, pricing, inventory, social media) and displays or processes it within WordPress. The second is exposing WordPress data via JSON – extending the WordPress REST API with custom endpoints, registering custom post type data with the REST API, or building entirely custom JSON endpoints for a specific integration requirement.

Common WordPress JSON API use cases include headless WordPress front ends (Next.js or Gatsby consuming WordPress content via REST API), mobile applications using WordPress as a back end, WooCommerce order and product management via the WooCommerce REST API, and custom integrations between WordPress and other business systems. Our guide on the WordPress REST API and custom fields covers how custom field data is exposed through the API. Acf WordPress Rest Api Custom Fields.

JSON API work on WordPress projects typically involves:

• Building custom REST API endpoints – registering new routes in WordPress that return specific data in a custom format for a specific integration requirement.
• Extending existing WordPress REST API responses – adding custom fields, ACF data, or computed values to default REST API responses for posts, users, or products.
• Consuming external JSON APIs – fetching data from third-party services on a schedule or on-demand and incorporating it into WordPress content or functionality.
• WooCommerce REST API integration – managing products, orders, customers, and coupons programmatically from external systems via the WooCommerce JSON API.
• Building a REST API back end for a mobile app – designing endpoints that serve a React Native or Flutter app with WordPress data.
• Webhook handling – receiving JSON payloads from external services (Stripe, Zapier, Salesforce) and processing them within WordPress.

JSON API development requires both WordPress knowledge and general API design knowledge. Look for developers who understand REST principles – proper use of HTTP methods (GET, POST, PUT, DELETE), status codes, authentication patterns, and versioning. A WordPress developer who has only worked with the admin interface may not have this background.

For custom endpoint development, ask how they handle authentication and authorisation. Public endpoints that return sensitive data, or endpoints that accept writes, need proper authentication. The WordPress REST API supports nonces (for browser-based requests), application passwords, and JWT tokens – the right choice depends on the integration context.

For external API consumption, ask how they handle API failures. An integration that crashes the WordPress site when a third-party API is unavailable is a production problem. Proper error handling, caching of API responses, and graceful degradation are important for any integration that depends on an external service.

Common JSON API problems in WordPress: Acf WordPress Rest Api Custom Fields.

• Custom endpoint returning 404 – the endpoint was registered but WordPress permalinks were not flushed after registration. Go to Settings > Permalinks and save to flush the rewrite rules.
• REST API returning 401 Unauthorized – authentication is required for the endpoint and the request is not including valid credentials. Check that the authentication method matches what the endpoint expects.
• External API call timing out in WordPress – WordPress’s default HTTP timeout is 5 seconds. External APIs that are slow or unreliable hit this limit. Increase the timeout using the http_request_timeout filter or move the API call to a background job.
• CORS error when JavaScript calls the WordPress REST API – the WordPress REST API is being called from a different domain. Add CORS headers to the REST API response using the rest_pre_serve_request filter.
• ACF fields not appearing in REST API response – ACF fields need to be explicitly registered with show_in_rest set to true in the field group settings or via register_rest_field().

Custom REST API endpoints need to be maintained when WordPress core updates change the REST API infrastructure. Endpoint changes in major WordPress versions occasionally break custom integrations. Testing integrations after WordPress major version updates is important.

External API integrations need monitoring as the external API evolves. Version deprecation notices, authentication method changes, and response format updates require updates to the WordPress integration code. Subscribing to the external API’s changelog or developer newsletter helps anticipate breaking changes before they happen.

When posting a JSON API project on Codeable, describe both sides of the integration – what system is sending or receiving data, what data is being exchanged, and what format it needs to be in. Include API documentation links for any external service involved. Describe the authentication model if known.

For custom endpoint projects, describe what data the endpoint needs to return and who will call it – a JavaScript front end, a mobile app, or an external service. This determines the authentication approach and response format requirements.