API keys are the most common auth for developer APIs (Stripe, SendGrid). You send one key that both identifies and authenticates your app. There is no username — the key is everything.
In a header (recommended)
curl https://api.ifsjaipur.cloud/playground/auth/api-key -H "x-api-key: YOUR_API_KEY"In the query string (weaker)
curl "https://api.ifsjaipur.cloud/playground/auth/api-key-query?api_key=YOUR_API_KEY"Both authenticate the same app, but the query-string version is weaker: URLs get logged by servers, proxies, and browser history, so the key leaks. Prefer the header.
Tip · In n8n: use a "Header Auth" credential (name: x-api-key, value: your key) rather than hardcoding the header on the node.