What is the difference between 301 and 302 redirects?

301 (Moved Permanently) tells browsers and search engines the URL has permanently moved. Browsers update bookmarks, search engines transfer link equity. 302 (Found) is temporary — search engines keep the original URL indexed, browsers don't update bookmarks. Use 301 for permanent URL changes and migrations; 302 for temporary redirects like A/B tests.

What is the difference between 401 and 403?

401 Unauthorized means authentication is required but missing or invalid — the user needs to log in or provide valid credentials. 403 Forbidden means the user is authenticated but does not have permission to access the resource. The term "Unauthorized" in 401 is historically misleading — it actually means "unauthenticated".

Does a redirect chain hurt SEO?

Yes. Redirect chains waste Googlebot's crawl budget on intermediate URLs with no content. Each hop also slightly degrades link equity transfer through 301 redirects. More practically, chains add latency. Fix chains by configuring your server to redirect directly from the original URL to the final destination, eliminating intermediate hops.

What does a 304 Not Modified response mean?

A 304 means the resource has not changed since the browser last fetched it. The browser sent a conditional GET request (with If-None-Match or If-Modified-Since headers), and the server confirmed the cached version is still current. The browser uses its cached copy, saving bandwidth. This is the correct caching behavior — it means your server and browser are working together efficiently.

What should I return for a deleted resource — 404 or 410?

410 Gone is more precise for permanently deleted content. It signals to search engines that the resource is intentionally gone and should be de-indexed (crawlers respect this faster than 404). Use 404 when the resource may have been temporarily removed or moved without a redirect. Use 410 when you want search engines to remove the URL from their index as quickly as possible.

Tools16 min read·PublicSoftTools Team·June 2026

HTTP Status Codes & Redirect Chains: Complete Debugging Guide

Master HTTP status codes, understand redirect chains, inspect response headers, and debug website issues. The free HTTP Status Checker shows the full redirect chain and all response headers for any URL — no signup required.

How HTTP Requests Work

HTTP (HyperText Transfer Protocol) is the protocol underlying every web page load. Designed by Tim Berners-Lee in 1989 and standardized in HTTP/1.1 (RFC 2616, 1999), HTTP defines how clients (browsers, apps, API consumers) and servers communicate. HTTP/2 (2015) and HTTP/3 (2022) added performance improvements but the status code system remained backward-compatible.

When a browser navigates to a URL:

DNS resolution — the domain name is resolved to an IP address
TCP/TLS handshake — a connection is established (TLS adds the HTTPS encryption layer)
HTTP request — the browser sends a GET request with headers
HTTP response — the server replies with a status code, headers, and body
Rendering — the browser parses HTML, requests sub-resources (CSS, JS, images), and renders the page

The status code in step 4 is the most important diagnostic signal. It tells the client in three digits whether the request succeeded, failed, needs further action, or landed at the wrong address.

Complete HTTP Status Code Reference

1xx — Informational

Provisional responses sent before the final response. Rarely seen in browser DevTools but important for HTTP/2 server push and long-polling.

Code	Name	Meaning
100	Continue	Client should send the request body. Used with `Expect: 100-continue`
101	Switching Protocols	Server is switching to the protocol specified in `Upgrade` header (e.g. WebSocket)

2xx — Success

Code	Name	Meaning
200	OK	Standard success. Request succeeded, response body contains the result
201	Created	POST/PUT succeeded and created a new resource. `Location` header points to it
202	Accepted	Request accepted for processing, but not yet complete (async jobs)
204	No Content	Success but no response body (common for DELETE and some PUTs)
206	Partial Content	Server fulfilled a `Range` request — used for video streaming and resumable downloads

3xx — Redirection

Code	Name	SEO impact	Use when
301	Moved Permanently	Passes ~99% of link equity	Permanent URL change, domain migration
302	Found (Temporary)	No link equity transfer	Temporary redirect, maintenance pages
304	Not Modified	Not applicable	Browser uses cached version — great for performance
307	Temporary Redirect	No equity transfer	Temporary, but preserves HTTP method (POST stays POST)
308	Permanent Redirect	Same as 301	Permanent, preserves HTTP method (use over 301 for non-GET)

4xx — Client Errors

Code	Name	Meaning
400	Bad Request	Malformed request syntax, invalid parameters
401	Unauthorized	Authentication required or failed
403	Forbidden	Authenticated but not permitted
404	Not Found	Resource does not exist at this URL
405	Method Not Allowed	GET used where only POST accepted (or vice versa)
409	Conflict	Request conflicts with current server state (e.g. duplicate unique key)
410	Gone	Resource permanently deleted — stronger than 404 for SEO de-indexing
422	Unprocessable Entity	Request understood but validation failed (common in REST APIs)
429	Too Many Requests	Rate limit exceeded. Check `Retry-After` header

5xx — Server Errors

Code	Name	Meaning
500	Internal Server Error	Unhandled exception. Check server logs
502	Bad Gateway	Upstream server returned invalid response (common during deploys)
503	Service Unavailable	Server overloaded or in maintenance. Temporary
504	Gateway Timeout	Upstream server took too long to respond

Redirect Chains: What They Are and Why They Matter

A redirect chain occurs when URL A redirects to URL B, which redirects to URL C. Each hop requires a full HTTP round-trip: DNS resolution, TCP connection, TLS handshake, request, response. On a 100ms latency connection, each redirect adds ~100ms of unavoidable delay before the browser can even start loading the actual page.

Example chain

http://example.com        → 301 → https://example.com
https://example.com       → 301 → https://www.example.com
https://www.example.com   → 200 OK (final destination)

Total: 3 HTTP requests, ~600ms added latency at 200ms/hop

Performance impact

Redirect hops	Added latency (200ms/hop)	Impact
0	0ms	Ideal
1	~200ms	Acceptable (HTTP → HTTPS)
2	~400ms	Noticeable on slow connections
3+	600ms+	Poor UX; investigate and consolidate

SEO implications

Google passes PageRank (link equity) through 301 and 308 redirects, but each hop in a chain slightly degrades the equity transfer. More practically: Googlebot has a finite crawl budget. Long redirect chains waste crawl budget on intermediate URLs that provide no value, reducing the number of real pages crawled per day. This directly impacts how quickly new content gets indexed.

Use 301 (not 302) for permanent moves to pass equity. Fix multi-hop chains by configuring your server to redirect directly from the original URL to the final destination.

Key Response Headers

Header	Example	Purpose
`Content-Type`	`text/html; charset=utf-8`	How browser should interpret the body
`Cache-Control`	`max-age=3600, public`	Caching policy — how long and by whom
`ETag`	`"abc123def"`	Version fingerprint for conditional GET requests
`Strict-Transport-Security`	`max-age=31536000`	Force HTTPS for future requests (HSTS)
`Content-Security-Policy`	`default-src 'self'`	Whitelist for scripts and resources (XSS prevention)
`X-Frame-Options`	`DENY`	Prevent page from being embedded in iframes (clickjacking)
`Access-Control-Allow-Origin`	`https://app.example.com`	CORS — which origins may access this resource
`Vary`	`Accept-Encoding, Accept-Language`	Which request headers affect the cached response

Using the HTTP Status Checker

Open the HTTP Status Checker
Paste any URL (with or without https://)
Click Check Status
The tool shows the full redirect chain with status codes at each hop, final status, response time, and all response headers
For batch checking, switch to Batch mode and paste multiple URLs (one per line)

Check HTTP Status Codes Free Online

Full redirect chain, response headers, batch URL checking — no signup required.

Open HTTP Status Checker