HTTP Status Codes: Complete Reference Guide | Free Tool

A Absolutely — especially 302 redirects to external URLs. Attackers exploit open redirects to phish credentials or spread malware. Our reference lists security implications alongside each code. Check the 3xx section for guidance on validating redirect destinations. A 200 on a phishing page doesn't mean it's safe either. Use this tool as a quick sanity check when auditing endpoints during code reviews.

A Both are temporary redirects, but they carry different meanings. A 302 tells browsers the move is temporary — search engines may not transfer link equity the same way. A 307 is stricter, preserving the request method (e.g., POST stays POST). For SEO, neither passes full ranking power like a 301 does. Our tool’s 3xx section shows you exactly when to use each. If you're doing site maintenance, stick with a 302; for permanent moves, never skip the 301.

A A 502 Bad Gateway means your backend server isn't responding properly to the proxy or load balancer. During traffic spikes, this often happens when server resources get exhausted — think connection limits exceeding 250 concurrent users on a shared host. Check your server logs for timeouts or database connection pool exhaustion. Our tool's 5xx section breaks down the exact server-side causes, helping you explain to your hosting provider exactly what's failing. Pro tip: stagger your CDN's origin pull requests during high traffic.

A Both are 1xx informational codes, but they serve completely different jobs. 100 Continue means the server got your initial request headers and you should keep sending the body. 101 Switching Protocols appears when the server agrees to upgrade the connection — think WebSocket handshakes or HTTP/2 upgrades. Our tool's 1xx section explains each protocol scenario clearly. Filter by '1xx' to see them side by side. Handy tip for QA testers: if your WebSocket connection keeps dropping, verify the 101 response is being sent.

A Not necessarily. A 503 Service Unavailable often means temporary overload, like your server hitting 500 concurrent database connections. Your site might come back within minutes. Our tool’s 5xx section explains each subtype — for example, a 503 with a Retry-After header is different from one without. Check your server logs before panicking. Pro tip: configure a custom 503 page with a refresh meta tag to help users retry automatically.

A A 304 fires when your browser sends an If-Modified-Since or If-None-Match header, and the server says nothing changed. That saves a full download, but only if you're caching correctly. Check your server logs — 304s should appear alongside 200s for the same resource. If you never see them, your cache headers are off. Set Cache-Control max-age to at least 3600 seconds for static assets. Our tool's 3xx section lists the exact conditions for triggering a 304. That's where you'll spot misconfigurations fast.

A A 404 isn't automatically a failure. Many teams deliberately return 404 for soft-deleted items or draft pages that shouldn't be crawlable. But if you're seeing 404s on URLs that once had real traffic, that's a red flag — you've lost link equity and user trust. Use our search to check the 3xx section for 410 Gone, which tells search engines the removal is permanent. For a quick fix, redirect old URLs to their closest live equivalent. Check your analytics for 404 frequency before deciding.

A Filtering client-side problems takes under ten seconds when you use our instant search bar. Type 400 into the box to isolate every request syntax issue immediately. You won't waste time scrolling past successful 200 codes or 5xx server faults. Try narrowing your view by typing specific terms like payload or forbidden right now.

A Our live reference requires an active internet connection since it updates dynamically with new specifications. But you can easily bookmark the main page before takeoff or print the core 2xx and 4xx tables directly from your browser. Try typing common codes like 401 or 403 into the filter box right now to test its responsiveness before you leave. Next time you board a plane, you'll still have those critical error definitions ready on your cached screen.

A Your token payload might look completely valid, but the signature verification failed on the server side. Check if your secret key matches the environment variable. Use our 4xx filter to review the exact definition of Unauthorized alongside related token errors like 403. Pro tip: always verify your token expiration timestamps in epoch format before making authenticated API calls.