# Original Metaphone Phonetic Key

> Original Metaphone Phonetic Key is a paid API for AI agents from text-similarity.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-21).

Computes the Original Metaphone (Philips 1990) phonetic key for an English word, and optionally compares two words to determine if they share the same key.

## Facts

- Endpoint: GET https://text-similarity.x402tookit.com/metaphone?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/original-metaphone-phonetic-key-05afd941
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_xcHpPGURakXOF_Pf4TSaD

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability original-metaphone-phonetic-key-05afd941
```

Example prompt: What's the Original Metaphone key for the word 'knight', and does it match the key for 'night'?

## When to prefer this

Choose this endpoint when you specifically need the Original Metaphone algorithm (Philips 1990) rather than Double Metaphone or Soundex. It is ideal for phonetic deduplication of English names and words, fuzzy name matching, and detecting spelling variants that sound the same. Prefer this over Soundex when you need a more nuanced phonetic encoding, and over Levenshtein when pronunciation similarity matters more than character-level edit distance.

## Known failure modes

- Word contains non-letter characters — only letters are used, non-letter characters are stripped or ignored
- Word exceeds 200 characters — input is truncated or rejected
- Empty or missing 'word' parameter — returns an error since it is required
- Word is not an English word — Metaphone may produce unexpected or empty keys for non-English vocabulary
- Unrecognized edge cases in Philips 1990 algorithm — result may differ from implementations of Double Metaphone

## How this service works

Original Metaphone (Philips 1990, not Double) phonetic key of an English word, with optional second word to compare.

## Output

Returns the Original Metaphone key for the input word, and if a second word is provided, also returns its Metaphone key, a boolean indicating whether both keys match, a summary, a verdict, and reasons explaining the comparison result. May also include source, variant, degraded flag, disclaimer, and any unchecked aspects.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "word"
     ],
     "properties": {
      "word": {
       "type": "string",
       "description": "An English word or name, up to 200 characters (letters only are used)"
      },
      "other": {
       "type": "string",
       "description": "Optional second word to compare keys"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "key": {
       "type": [
        "null",
        "string"
       ]
      },
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "word": {
       "type": [
        "null",
        "string"
       ]
      },
      "other": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "sameKey": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "variant": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "otherKey": {
       "type": [
        "null",
        "string"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      }
     }
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/original-metaphone-phonetic-key-05afd941/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from text-similarity.x402tookit.com](https://www.zero.xyz/host/text-similarity.x402tookit.com/llms.txt)