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🌐 HTTP Status Codes
You see 502 in your logs and want to know what to do about it. Or you are designing an API and trying to decide between 400 and 422. This is the searchable reference, organized by category, with notes on when each code actually shows up in practice and not just in the RFC.
Examples
401 = "you are not authenticated" · 403 = "you are, but not allowed"500 = generic server error · 502 = upstream broken · 503 = maintenance · 504 = upstream slowFrequently asked questions
401 vs 403?
401: "I do not know who you are" — log in. 403: "I know who you are but you cannot do this" — permission issue.
301 vs 302?
301 = permanent (search engines update). 302 = temporary. Use 308/307 if the HTTP method must be preserved (POST stays POST).
About this calculator
HTTP Status Codes runs entirely in your browser using standard formulas. No data is sent to any server. We don't share your inputs with lenders, brokers, or anyone else — there's no funnel and no follow-up email.
Related tools
- 🔌 TCP / UDP Port Reference — Searchable reference of common TCP/UDP ports and the services that use them.
- 📚 DNS Record Types Reference — What each DNS record type does (A, AAAA, MX, TXT, CNAME, SRV, CAA, etc.).
Why this tool
vs typical free network-tools sites
| NetToolset | Typical free site | |
|---|---|---|
| Price | Free | Free |
| Signup required | No | Often (for advanced features) |
| Ads inside the tool | No | Yes (banner + interstitial) |
| Logs your IP / queries | No | Yes (often resold) |
| Data sent to a server | Math runs in browser; lookups hit Cloudflare DoH directly | Yes (all goes through their server) |
| Open source | Yes | No |
| Bookmarkable URL per tool | Yes | Mixed |
| Multilingual | EN / ES / PT / FR / DE | Usually EN only |
| Loads in under 1s | Yes (static) | Often slow (ad tracking) |