HTTP Status Message

Look up a status-code description in the IANA 2025-09-15 registry snapshot, with an explicit unknown result for unassigned codes.

Description

HTTP status codes identify response classes, while registry descriptions supply standard names.

HTTP status codes identify response classes, while registry descriptions supply standard names. This lookup uses a fixed IANA registry snapshot rather than a live registry query.^{[1, 2]}

Look up a status-code description in the IANA 2025-09-15 registry snapshot, with an explicit unknown result for unassigned codes.

When to use HTTP Status Message

Use this tool to look up a status-code description in the IANA 2025-09-15 registry snapshot, with an explicit unknown result for unassigned codes.

Prepare the header field value, cookie records or status code requested. Supply field values without a header-name prefix and preserve syntax for the parser to inspect.

How to use HTTP Status Message and understand its results

Prepare the header field value, cookie records or status code requested. Supply field values without a header-name prefix and preserve syntax for the parser to inspect.
Enter status using the field table and calculation rules, then run the tool.
Read message, known. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
status	HTTP status code.	integer; minimum: 100; maximum: 599	Required

Enter an integer code 100–599. Return its snapshot description and known flag. An unassigned code is a successful result with an empty message and false; entries labeled (Unused) still return true. The snapshot is dated 2025-09-15.

message=snapshot[status] or empty; known=message is nonempty

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
message	Registry description, empty for an unassigned code.	string; maximum length: 1000000
known	Whether the snapshot assigns this status.	boolean

json

{
  "input": {
    "status": 422
  },
  "output": {
    "message": "Unprocessable Content",
    "known": true
  }
}

Limitations and assumptions

No response is fetched or diagnosed. Registry changes after the snapshot are not reflected.

Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors. A successfully returned false flag is an evaluated outcome; its meaning is explained above.

Alternative or Complementary methods

Use HTTP Status Category: Classify an HTTP response status code into its RFC 9110 1xx–5xx response class. For a complementary task, use HTTP Header Name Normalizer: Validate an HTTP field name as an RFC token and convert it to lowercase for case-insensitive lookup.

Further background: HTTP Status Code Registry.

References

HTTP Status Message — tool.io
HTTP Status Code Registry — Internet Assigned Numbers Authority

Similar or alternative tools

HTTP Status Category
Classify an HTTP response status code into its RFC 9110 1xx–5xx response class.
HTTP Header Name Normalizer
Validate an HTTP field name as an RFC token and convert it to lowercase for case-insensitive lookup.