Advanced · 9 lessons

APIs

APIs (Application Programming Interfaces) let software systems communicate programmatically. Hosting APIs manage domains, DNS, servers, and billing. Understanding REST APIs is essential for automation and modern web development.

Key Concepts

REST API HTTP Methods (GET/POST/PUT/DELETE) JSON Authentication (API Keys/OAuth) Webhooks Rate Limiting API Documentation cURL & Postman

Key Takeaways

✓ REST APIs use HTTP methods on URL endpoints returning JSON data.
✓ Authenticate API requests with keys, tokens, or OAuth 2.0.
✓ Webhooks push events to your server — no polling needed.
✓ Always respect rate limits and handle errors gracefully.

Lessons in This Topic

API Fundamentals

How applications talk to each other.

APIs define contracts: send this request, get that response. REST uses HTTP methods: GET (read), POST (create), PUT (update), DELETE (remove). JSON is the standard data format. Status codes: 200 OK, 201 Created, 400 Bad Request, 401 Unauthorized, 404 Not Found, 500 Server Error.

Working with Hosting APIs

Automate domain, DNS, and server management.

Cloud providers offer APIs for everything: create VM, add DNS record, manage SSL. Example: Cloudflare API to update DNS programmatically. WHMCS API for billing automation. Use SDKs (boto3 for AWS) or raw HTTP with cURL/Postman.

Authentication & Security

API keys, OAuth, and best practices.

Never expose API keys in frontend JavaScript. Store in environment variables. Use OAuth 2.0 for user-delegated access. Rotate keys periodically. Scope keys to minimum required permissions. Log all API access for audit trail.

Webhooks & Event-Driven Automation

React to events in real time.

Webhooks: server A sends HTTP POST to your URL when event occurs. Example: payment completed → webhook → provision hosting account. Verify webhook signatures to prevent spoofing. Return 200 quickly; process async if heavy. Retry failed deliveries with exponential backoff.

Testing APIs with Postman & cURL

Debug and document API integrations.

cURL: `curl -H "Authorization: Bearer TOKEN" https://api.example.com/domains`. Postman: GUI for building, testing, and documenting API requests. Save collections for team sharing. Use environment variables for keys. Monitor response times and error rates.