Back to All Questions
Question 15 of 100
Basic API Testing
Beginner
Q15: What is a Request Header in API Testing?
🏷️Core Concept
What is a Request Header in API Testing?
Key Takeaways & Architecture Summary
- ✓Contains metadata that configures how the request should be processed.
- ✓Accept: Declares the data format the client expects back.
- ✓Content-Type: Declares the media format of the payload being sent.
- ✓Authorization: Transmits tokens, API keys, or basic credentials.
Direct Answer Summary
A Request Header is a key-value metadata pair sent within the HTTP request header block. It provides essential metadata to the server, detailing the client's identity, authenticating access tokens, configuring payload content formats (via `Content-Type`), declaring expected response formats (via `Accept`), and passing cookie states.
⚠️ Senior Engineering Warning (Red Flag)
Avoid mismatching Content-Type with your payload structure. If you send a JSON string but leave Content-Type as "text/plain", the server may reject it with an HTTP 415 Unsupported Media Type error.
💡 STAR Architectural Explanation & Pro Tip
Headers separate data from transport configuration. This allow proxies, load balancers, and firewalls to authenticate, route, and cache requests without opening the body payload.
PlaywrightApiTest.ts
Playwright API// Injecting custom headers using Playwright API
await request.get('/api/v1/jobs', {
headers: {
'Accept': 'application/json',
'X-Client-Type': 'Web-App-2026'
}
});