Help your users understand what every HTTP response code means.
HTTP Status Code Lookup decodes any HTTP status code by returning its standard name and detailed description. Provide a numeric code to inspect its meaning and response behavior across standard ranges, and add details=true for a link to the defining RFC section, plus on paid plans its retry and caching behavior and the headers that go with it.
Try it — live request, no key required
No key required to try it. Get a key to use it in your app.
{
"status": "ok",
"error": null,
"data": {
"code": 404,
"name": "Not Found",
"description": "The requested resource could not be found",
"category": "Client Error",
"is_error": true,
"is_success": false,
"is_redirect": false,
"is_informational": false,
"registry_name": "Not Found",
"spec": "RFC 9110, Section 15.5.5",
"spec_url": "https://www.rfc-editor.org/rfc/rfc9110#section-15.5.5",
"is_retryable": false,
"is_cacheable_by_default": true,
"related_headers": []
}
}
About the HTTP Status Code Lookup API
HTTP Status Code Lookup works by querying the HTTP status codes registered with IANA and defined across RFCs 9110, 6585, 4918 and others. Returns the status code name, description, category and boolean flags; with details=true it also returns a link to the defining RFC section, and on paid plans the current registry name, the RFC section itself, whether the code is safe to retry, whether RFC 9110 lets caches store it by default, and the headers the spec pairs with it (Location, Retry-After, WWW-Authenticate, Allow and so on).
What people use it for
- API Development
- Quickly reference HTTP status codes while developing and debugging APIs
- Error Handling
- Understand status codes when implementing error handling and response logic
- Documentation
- Generate status code documentation and error message templates for APIs
- Troubleshooting
- Diagnose HTTP errors and understand response codes during debugging
Ways to call it
One endpoint, many ways in — REST with JSON, XML, YAML and CSV, plus GraphQL and an MCP interface for AI agents.
- JSON
- Default REST response
- XML
- Markup format
- YAML
- Human-readable
- CSV
- Tabular export
- GraphQL
- Query language
- MCP
- For AI agents
Other ways to use HTTP Status Code Lookup
Same data, same APIVerve account, same credit balance — one key works on all of them.
Which HTTP status codes are covered?
Does it support custom or proprietary status codes?
How far does the Starter plan go for status code lookups?
Are status categories and error flags included on the Free plan?
Can I display these status code definitions in a commercial tool?
Can it tell me whether to retry a request or which header to read?
Request parameters — GET /v1/httpstatuslookup
Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them. Anything not listed here is dropped rather than passed through.
Required
| Parameter | Type | Example | Description |
|---|---|---|---|
codeRequired | integer | 404 | HTTP status code to lookup range 100-599 |
Optional
| Parameter | Type | Example | Description |
|---|---|---|---|
detailsOptional | boolean | true | Also return the registry name, defining RFC section and link, retry and default-caching flags, and related headers default false |
curl "https://api.apiverve.com/v1/httpstatuslookup?code=404&details=true" \
-H "x-api-key: YOUR_API_KEY"Authentication
Send your key in the x-api-key header. That is the only auth step — no token exchange, and no per-endpoint scope to configure.
| Header | When | Value |
|---|---|---|
x-api-keyRequired | Every request | Your API key. Header names are case-insensitive, so X-API-Key is the same header. |
AuthorizationAlternate | Instead of the above | Bearer <key> — for clients that only expose bearer auth. Resolves to the same account and the same billing. |
A 401 means the key is missing, invalid or expired. A 403 means the key is valid but not permitted here — blocked by a key restriction or an IP allow-list. Running out of credits is a 429.
Response — GET /v1/httpstatuslookup
Every APIVerve endpoint returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape.
{
"status": "ok",
"error": null,
"data": {
"code": 404,
"name": "Not Found",
"description": "The requested resource could not be found",
"category": "Client Error",
"is_error": true,
"is_success": false,
"is_redirect": false,
"is_informational": false,
"registry_name": "Not Found",
"spec": "RFC 9110, Section 15.5.5",
"spec_url": "https://www.rfc-editor.org/rfc/rfc9110#section-15.5.5",
"is_retryable": false,
"is_cacheable_by_default": true,
"related_headers": []
}
}
Response fields
Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.
| Field | Type | Example | Description |
|---|---|---|---|
code | number | 404 | HTTP status code number |
name | string | "Not Found" | Standard name of the status code |
description | string | "The requested resource could not be found" | Detailed description of the status code |
categoryPremium | string | "Client Error" | The classification of the status code by its leading digit: Informational, Success, Redirection, Client Error, or Server Error |
is_errorPremium | boolean | true | Whether the status code represents a client or server error (4xx or 5xx) |
is_success | boolean | false | Whether the status code represents a successful response (2xx) |
is_redirect | boolean | false | Whether the status code represents a redirection (3xx) |
is_informational | boolean | false | Whether the status code represents an informational response (1xx) |
registry_namePremium | string | "Not Found" | Current name in the IANA HTTP status code registry, which can differ from the common name (413 is now Content Too Large). Returned with details=true |
specPremium | string | "RFC 9110, Section 15.5.5" | The RFC, and section where the registry gives one, that defines the code. Returned with details=true |
spec_url | string | "https://www.rfc-editor.org/rfc/rfc9110#section-15.5.5" | Link to the defining RFC section on rfc-editor.org. Returned with details=true |
is_retryablePremium | boolean | false | Whether the code signals a transient condition, so the same request may succeed later (408, 425, 429, 500, 502, 503, 504). Returned with details=true |
is_cacheable_by_defaultPremium | boolean | true | Whether RFC 9110 Section 15.1 lets a cache store this response without explicit freshness information. Returned with details=true |
related_headersPremium | array | [] | Headers the defining spec pairs with this code, such as Location for redirects or Retry-After for 429 and 503. Empty when there are none. Returned with details=true |
Response headers
Every response carries your balance, so your own code always knows where it stands without polling anything. All four are exposed to browsers through CORS.
| Header | What it carries |
|---|---|
x-api-remaining-credits | Credits left in the current cycle |
x-api-credits-used | Credits spent in the current cycle |
x-api-max-credits | The allowance for the cycle |
x-api-version | Version of the endpoint that answered |
Errors
Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change.
| Status | Meaning | What to do |
|---|---|---|
400 | Input was rejected | Read error; it names the parameter that has to change. |
401 | Key missing or invalid | Check the header name and the key value. |
403 | Key valid, but not permitted here | A key restriction or an IP allow-list — never a bad key. |
429 | Rate limited, or out of credits | Read error to tell them apart, then back off or top up. |
What a call costs — 1 credits per call
Credits are shared across every APIVerve API — one balance, one key, one bill. Failed requests never count against it, so a rejected input costs nothing.
| Plan | Per month | Credits | HTTP Status Code Lookup calls | Per 1,000 calls |
|---|---|---|---|---|
| Free | Free | 200 | 200 | Free |
| Starter | $29.99 | 200,000 | 200,000 | $0.15 |
| Pro | $99.99 | 1,000,000 | 1,000,000 | $0.10 |
| Mega | $299.99 | 4,000,000 | 4,000,000 | $0.07 |
Calls are what the credits buy at this API's rate — spend them here, on any of the other APIs, or across both. Nothing is reserved per endpoint.
Call it from cURL — GET /v1/httpstatuslookup
No SDK to install — this is a plain HTTPS call to /v1/httpstatuslookup with your key in the x-api-key header. Swap in a real key and it runs as-is.
curl "https://api.apiverve.com/v1/httpstatuslookup" \
-H "x-api-key: YOUR_API_KEY"Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from Node.js — GET /v1/httpstatuslookup
Install the Node.js SDK, then call the HTTP Status Code Lookup API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.
npm install @apiverve/httpstatuslookupconst res = await fetch("https://api.apiverve.com/v1/httpstatuslookup", {
headers: { "x-api-key": "YOUR_API_KEY" },
});
const { data } = await res.json();
console.log(data);Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from Python — GET /v1/httpstatuslookup
No SDK to install — this is a plain HTTPS call to /v1/httpstatuslookup with your key in the x-api-key header. Swap in a real key and it runs as-is.
import requests
res = requests.get(
"https://api.apiverve.com/v1/httpstatuslookup",
headers={"x-api-key": "YOUR_API_KEY"},
)
print(res.json()["data"])Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from C# / .NET — GET /v1/httpstatuslookup
Install the C# / .NET SDK, then call the HTTP Status Code Lookup API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.
dotnet add package APIVerve.API.HTTPStatusCodeLookupusing var client = new HttpClient();
client.DefaultRequestHeaders.Add("x-api-key", "YOUR_API_KEY");
var json = await client.GetStringAsync("https://api.apiverve.com/v1/httpstatuslookup");
Console.WriteLine(json);Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from Go — GET /v1/httpstatuslookup
No SDK to install — this is a plain HTTPS call to /v1/httpstatuslookup with your key in the x-api-key header. Swap in a real key and it runs as-is.
req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/httpstatuslookup", nil)
req.Header.Set("x-api-key", "YOUR_API_KEY")
res, _ := http.DefaultClient.Do(req)
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from PHP — GET /v1/httpstatuslookup
No SDK to install — this is a plain HTTPS call to /v1/httpstatuslookup with your key in the x-api-key header. Swap in a real key and it runs as-is.
$ch = curl_init("https://api.apiverve.com/v1/httpstatuslookup");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-api-key: YOUR_API_KEY"]);
$response = curl_exec($ch);
echo $response;Resources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Call it from Ruby — GET /v1/httpstatuslookup
No SDK to install — this is a plain HTTPS call to /v1/httpstatuslookup with your key in the x-api-key header. Swap in a real key and it runs as-is.
require "net/http"
uri = URI("https://api.apiverve.com/v1/httpstatuslookup")
req = Net::HTTP::Get.new(uri)
req["x-api-key"] = "YOUR_API_KEY"
res = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) { |h| h.request(req) }
puts res.bodyResources
Also published for
Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.
Zero-code embed — one snippet, no backend
Drop an interactive HTTP Status Code Lookup form onto any page. The widget calls the API for you, so no key ever appears in your markup and there is nothing to deploy.
Changelog — HTTP Status Code Lookup API
Every change to this endpoint, newest first. Breaking changes ship as a new version and the previous one keeps serving — response fields are added, never removed or retyped in place, so an integration written against v1 keeps working.
Entries are picked up from dated catalog snapshots, so the first one appears after the next snapshot that moves something. A period where nothing changed produces no entry — silence is a valid changelog for the HTTP Status Code Lookup API.
Reference Data
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