HTTP status code reference
Look up RFC-style 1xx–5xx responses, skim typical causes and fix hints, filter by class, or paste a log line to extract every three-digit HTTP code in the text. Everything runs in your browser — no API calls for lookup.
Found the signal in the noise. CloudyBot can hit your health URL on a schedule, classify 5xx vs 429, open a real browser session for deeper checks, and notify you before customers do — with published plan caps.
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Parse log / curl output
How it works
HTTP status codes are three-digit integers returned in the status line of an HTTP response (for example HTTP/1.1 404 Not Found). The first digit defines the class: 1xx informational, 2xx success, 3xx redirection, 4xx client error, 5xx server error. Semantics for the core protocol are standardized primarily in RFC 9110 (HTTP Semantics), with method-specific behavior in RFC 9112 (HTTP/1.1) and RFC 9113 (HTTP/2).
This page embeds a curated table of common registered codes plus a few widely seen vendor extensions (for example reverse-proxy and CDN-specific codes) so operators debugging real traffic see the same numbers their edge returns. The search box filters the grid by code, reason phrase, or keywords in the long description. Jump to code selects a chip when it exists and scrolls it into view. Extract codes recognizes HTTP/1.1 502-style status lines plus standalone three-digit numbers (100–599), dedupes in order of appearance, and prints a one-line hint when the code is in the table.
Nothing here performs a live HTTP request: you are reading a static reference. For production incidents, combine this lookup with your APM, load balancer logs, and origin health checks — or let an agent automate that loop.
Common use cases
- Decode a curl error when the CLI prints only
404or429without the full body. - Teach juniors the difference between
401,403, and419-style session expiry patterns. - Design REST APIs and pick consistent status codes for validation vs auth vs conflict.
- Read nginx / CDN logs where non-standard edge codes appear next to origin
5xx. - Write runbooks with correct phrases so alerts match RFC language.
- Prepare customer support macros that explain
503maintenance vs502upstream failure.
You just decoded an HTTP code. CloudyBot can watch the endpoint.
Example: “Every 5 minutes, GET https://api.example.com/health; if status is not 200 or latency exceeds 2s, post to Slack.” CloudyBot runs scheduled checks with a real browser session when you need more than a bare status code.
Free plan · No credit card · 60-second setup
HTTP 404, 500, 429, and the full 1xx–5xx map
Developers search for http status code list, rest api status codes, or specific errors like 502 bad gateway meaning and 429 too many requests fix. This reference groups codes by class, links to the authoritative RFC, and adds pragmatic troubleshooting text for the cases that show up most often in production: bad TLS to origin, auth header drift, oversized payloads, cache validators, and rate limits.
Frequently asked questions
Is this HTTP status reference free?
Yes. There is no signup, no usage counter, and no paywall. Use it as often as you like.
Is my log paste sent to your servers?
No. Search, filters, and log parsing run entirely in your browser. Open DevTools → Network to confirm no request carries your paste.
Which HTTP specification do the descriptions follow?
Standard 1xx–5xx entries align with semantics documented in RFC 9110 (HTTP Semantics) and related HTTP RFCs. Vendor-specific codes are labeled as non-standard in the reference text.
What is the difference between 401 and 403?
401 Unauthorized means authentication is required or failed — the client may retry with valid credentials. 403 Forbidden means the server understood the request but refuses to authorize it; retrying with the same identity often will not help without a policy change.
Why do I see 502 or 504 behind a reverse proxy?
502 Bad Gateway usually means an upstream server returned an invalid response to the proxy. 504 Gateway Timeout means the proxy did not receive a timely response from upstream. Check upstream health, timeouts, TLS to origin, and keep-alive settings.
What is CloudyBot?
CloudyBot is a hosted AI agent that can browse the web, use files, remember context across conversations, and run tasks on a schedule — with hard billing caps so you never get surprise overages. This reference is a small utility; the product is for when you want the machine to monitor and explain HTTP behavior instead of repeated manual lookups.
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