If you’ve ever said “the API isn’t working” without knowing why, the Network tab in Chrome DevTools is the first place you should look.
It shows you every request your app makes, what was sent, what came back, and where things went wrong.
Here’s how to actually use it.
Opening the Network Tab
- Open your site in Chrome
- Right-click anywhere → Inspect
- Click the Network tab
- Reload the page
Make sure the red recording dot is on, otherwise you won’t see anything.
What You’re Looking At
Every row represents a network request.
Key columns to understand:
- Name → the request URL or file name
- Status → HTTP status code (200, 404, 500, etc.)
-
Type → request type (
fetch,xhr,document,script) - Size → response size
- Time → how long the request took
If something is red, that’s usually where the problem is.
Filtering Requests (Very Important)
Real apps make lots of requests. Use filters to stay sane.
At the top, click:
- Fetch / XHR → for API requests
- JS / CSS / Img → for assets
Or type part of the endpoint into the filter input to narrow it down.
Inspecting an API Request
Click any request and you’ll see multiple tabs:
Headers
This is where you debug most issues.
- Request URL
- HTTP method
- Request headers
- Response headers
- Status code
This is where you catch:
- Wrong HTTP method
- Missing auth headers
- CORS issues
Preview
Shows a formatted version of the response (JSON, HTML, etc.).
If your UI is broken but the preview looks fine, the bug is likely frontend logic, not the API.
Response
Raw response body.
If the API returns an error message, it’ll usually be here.
Timing
Shows how long each part of the request took.
Useful for diagnosing:
- Slow APIs
- Backend performance issues
Common Problems You Can Debug Instantly
- 404 errors → wrong endpoint
- 401 / 403 → auth or permission issues
- 500 errors → backend bug
- CORS errors → missing headers on the server
- Requests never firing → frontend logic issue
Instead of guessing, the Network tab gives you proof.
Power Tips Most Devs Miss
- Enable Preserve log to keep requests after page navigation
- Enable Disable cache while DevTools is open
- Right-click a request → Copy as cURL to test it in the terminal
- Compare request headers between working and broken calls
Why This Matters
Most “frontend bugs” are actually network problems:
- Wrong data
- Failed requests
- Unexpected responses
Once you learn the Network tab, debugging becomes faster, calmer, and way more precise.
If you’re a developer and you’re not using the Network tab daily, you’re working harder than you need to.
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