HTTP Quoted String Unescaper

Strictly unescape one HTTP quoted-string with ASCII/obs-text validation; reject dangling escapes, CR/LF and unquoted input.

Description

Strictly unescape one HTTP quoted-string with ASCII/obs-text validation; reject dangling escapes, CR/LF and unquoted input.

An HTTP quoted-string decoder must distinguish escaped pairs from literal qdtext and reject forbidden control characters.

When to use this tool

Strictly unescape one HTTP quoted-string with ASCII/obs-text validation; reject dangling escapes, CR/LF and unquoted input.

Prepare the supplied value fields for this operation.
Compare the complete example with the representation used by your own input before carrying the result into another step.

How to use the tool and how it works

Enter value. Use the exact text syntax, units and index conventions explained below.
Run the tool. If input validation fails, correct the supplied fields before interpreting any result.
Read result.decoded. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.

Require surrounding double quotes. Decode backslash pairs only for permitted octet characters and accept unescaped qdtext excluding quote/backslash. Reject dangling escapes and invalid controls.^[1]

Input field	Meaning and representation	Accepted input
value	value.	Text; at most 8,192 UTF-16 code units, subject to the grammar above

Output field	Interpretation
result	Object containing the named outputs below.
result.decoded	The decoded value under the stated formula or text convention.

json

{
  "input": {
    "value": "\"a\\\"b\""
  },
  "output": {
    "result": {
      "decoded": "a\"b"
    }
  }
}

Limitations and assumptions

No Unicode transcoding or full header parsing occurs. JSON-style escape meanings such as backslash-n are not interpreted as a newline.
Every declared top-level field is required and unexpected fields are rejected. Numeric inputs must be finite; ordinary text fields are bounded to 8,192 UTF-16 code units, with tighter operation-specific limits where stated.
String lists have at most 128 entries of at most 128 code units; matrices have at most 128 rows and columns. Larger numeric lists and parsed JSON have separate bounded budgets. Nonfinite results and excessively large serialized outputs are rejected.
Indexes are zero-based and spans have an exclusive end unless explicitly stated otherwise. A valid false, null or empty-list result is distinct from malformed input.

Alternative or Complementary methods

Use a complete protocol or URL parser when interpreting a whole message or address. Preserve raw spelling when required and distinguish HTTP token grammar, URL path normalization and form-style query decoding.

References

Tool behavior and example: HTTP Quoted String Unescaper — tool.io

Similar or alternative tools

HTTP Quoted String Escaper
Escape a string as an HTTP quoted-string, quoting backslash and double quote; reject CR/LF, other controls and non-octet Unicode.
HTTP Content Length Decimal Parser
Parse Content-Length as exact unsigned ASCII decimal text without unsafe numeric conversion, signs, whitespace or exponent syntax.