URL Userinfo Last At Sign Boundary Tool

Description

Split authority at its last literal at sign.

Web protocol data has several layers: a complete message or URL, individual fields or components, and the literal tokens within them. Delimiter presence, spelling, comparison rules, and parser normalization can affect results. A check of one component needs its stated scope before it can be used in a larger parser or policy decision.

Split authority at its last literal at sign.

When to use this tool

Use URL Userinfo Last At Sign Boundary when you need one stated URL, header, or protocol-component check in a diagnostic or parser workflow. Supply the input level specified below.

How to use the tool and how it works

Enter authority. Use the units and conventions below.
Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
Read userinfo, hostPort, present. Inspect present before interpreting the associated values.

Split authority at its last literal at sign. Return text before it as userinfo, text after it as hostPort, and present; with no at sign return empty userinfo and the complete authority as hostPort. Reject carriage returns, newlines, slash, question mark, and hash.^[1]

Input field	Meaning and units	Accepted input
authority	Literal authority component, without a scheme or path.	Required. Text; maximum UTF-16 length 8192.

Output field	Interpretation	Returned shape
userinfo	Userinfo	Required. Text; maximum UTF-16 length 8192.
hostPort	Host Port	Required. Text; maximum UTF-16 length 8192.
present	Whether a literal at sign was present.	Required. Boolean.

json

{
  "input": {
    "authority": "user@name@example.com:80"
  },
  "output": {
    "userinfo": "user@name",
    "hostPort": "example.com:80",
    "present": true
  }
}

Limitations and assumptions

This is a lexical component splitter, not a URL or hostname validator. Encoded at signs are not decoded, earlier literal at signs remain in userinfo, and an empty side is allowed.
The field tables state structural bounds; the mechanics also specify cross-field constraints. Malformed inputs and unsupported domains cause errors. A successful false flag, empty branch value, or zero placeholder has the meaning stated above and is distinct from an input error.

Alternative or Complementary methods

Use a complete URL or header parser when the task involves an entire field or message. Test actual browser, server, or cache behavior separately when a security or protocol decision depends on more than this component.

References

Calculation and input contract: web/url-userinfo-last-at-sign-boundary — tool.io

Similar or alternative tools

parse/url
Split an absolute hierarchical URL into protocol, host, port, path, query, and fragment components. Bracketed IPv6 hosts and user-info prefixes are supported.
URL Fragment Empty Marker
Find the first literal hash in url.