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HTTP status codes: classes, meaning, and how to check them
An HTTP status code is a three-digit number in the server response: whether the page was served, a redirect is needed, or something failed. Browsers and search bots read it before they touch the HTML.
Below: code classes, what a webmaster should watch, and how to check URLs one by one or in bulk. Separate deep-dives on 200 and 502 are in related articles.
Wrong statuses (soft 200 on a removed page, redirect chains, mass 5xx) hurt crawl and indexing more than a typo in the footer.
How a server response works
The client requests a URL. The server replies with a line like `HTTP/1.1 200 OK`, headers, and a body. The code is a fast signal of what happened.
Search relies on status while crawling: 200 can be parsed as a document, 301 means follow the new address, 404 means do not expect content.
In the status line:
- protocol version
- three-digit code
- short text phrase (OK, Not Found…)
Classes 1xx–5xx
Codes group by the first digit. In SEO practice you mostly meet 2xx, 3xx, 4xx, and 5xx.
In short:
- 1xx — intermediate (rare on typical sites)
- 2xx — success (200 — page served)
- 3xx — redirect (301/302/307…)
- 4xx — client error (404, 403, 410…)
- 5xx — server error (500, 502, 503, 504…)
What matters to webmasters and SEO
Key landings should stably return 200. After a move — direct 301s without long chains. Removed URLs — don’t mask them with a homepage 200.
Watch 404 spikes in Webmaster and logs: broken internal links, outdated backlinks, export errors.
Red flags:
- product or service removed but still 200 with an empty template
- A→B→C→D redirect chains
- homepage returning 302 “somewhere”
- mass 5xx at night during bot peaks
How to check one URL
The most honest way is the response header: `curl -I https://example.com/page/` or the Network tab in the browser. Check the final code after redirects and the Location chain.
Online tools are handy, but for disputed cases check from a server or CI and account for CDN and geo.
One-URL checklist:
- final response code
- number of redirect hops
- www/https match the canonical
- no soft 404 by content
Checking the whole site
A crawler follows internal links and builds a status table. After a structure change, compare the list to the sitemap and priority URLs from Webmaster.
Bulk-checking external backlinks is separate: not everything should redirect to the homepage.
When to run a full crawl:
- domain or HTTPS move
- CMS or URL scheme change
- major template redesign
- error spikes in webmaster panels
How to build it into routine
Alerts on 5xx for main hosts, a monthly look at 404s, a check after every release. Statuses are hygiene — not one-shot SEO magic.
Fixing tech is part of site prep. Ranking growth for a keyword set after things stabilize is a separate, months-long process.
Mini ritual:
- uptime monitoring
- crawl of key templates
- top-404 review from logs
- a 301 map when URLs are removed
FAQ
Where can I see the status code?
DevTools → Network, `curl -I`, online checkers, crawlers (Screaming Frog and similar), and hosting or CDN reports.
What status is “normal” for an indexed page?
Usually 200. Permanent move — 301. Temporary — 302/307. Removed with no replacement — 404 or 410.
How does a 404 differ from a 410?
404 means “not found” (it may come back). 410 means “gone on purpose.” For permanently removed URLs, 410 is clearer for bots.
Why do status codes matter for SEO?
The bot decides whether to index a URL, whether to pass signals on redirect, and how much crawl budget to spend on errors.
What is a soft 404?
The page returns 200 but essentially says “nothing here.” For search that is worse than an honest 404: junk enters the index.
Should I check the whole site?
Yes after a move, CMS change, or mass URL edits. On a regular cadence — sample key templates plus a crawl.
Do 5xx errors kill rankings immediately?
A brief blip usually does not. Long downtime and mass 5xx do hurt crawl and trust in availability.
Soft 200 on deleted pages and redirect chains after a CMS move?
We’ll map statuses, fix soft-404 and 5xx alerts — crawl hygiene before ranking work.
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