Working with JSON APIs: From Request to Response Parsing

Modern software is built on APIs. Whether you're consuming a public service like GitHub or Stripe, or calling internal microservices, the pattern is the same: send a request, get a JSON response, parse it, and act on it. This guide covers the entire workflow.

The Request Cycle

• 1. Craft the request: Choose HTTP verb (GET, POST, etc.), build headers (Content-Type: application/json, Authorization), and create the body (JSON-serialized data).
• 2. Send it: Use fetch, axios, httpClient, or similar to transmit the request.
• 3. Receive the response: Parse the status code, headers, and body.
• 4. Handle errors: Check for 4xx (client errors) or 5xx (server errors) and retry intelligently.
• 5. Validate: Ensure the response JSON matches your expected schema before using it.

Common Patterns

Authentication Headers

• Bearer tokens: Authorization: Bearer eyJhbGc... (OAuth 2.0, JWTs)
• API keys: X-API-Key: sk_live_1234567890
• Basic auth: Authorization: Basic dXNlcjpwYXNz (base64-encoded username:password)

Pagination

Large result sets are split across pages. Check the response for "next" links or "page" metadata. Implement loops to fetch all pages.

Debugging with DevTools

• Open the Network tab in your browser DevTools
• Make the API request
• Click on the request → Preview tab to see the JSON response
• Check the Response Headers for rate-limit and cache directives
• Copy the response body and paste it into our JSON Validator