# Phonetic Similarity Compare (similarity.openverbs.com)

> Phonetic Similarity Compare (similarity.openverbs.com) is a paid API for AI agents from similarity.openverbs.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).

Checks whether two tokens sound alike using Soundex, Metaphone, or Double Metaphone, returning each token's phonetic codes and a boolean match result.

## Facts

- Endpoint: POST https://similarity.openverbs.com/v1/compare
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/phonetic-similarity-compare-similarity-openverbs-com-e306e7f7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_4SsLQGyzl8Tdhz4GZ0ekn

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 phonetic-similarity-compare-similarity-openverbs-com-e306e7f7 -d '<json body>'
```

Example prompt: Do 'Catherine' and 'Kathryn' sound the same? Use double-metaphone to compare them and tell me if they match phonetically.

## When to prefer this

Use this endpoint when you need a single yes/no phonetic match decision with supporting codes for two tokens, especially when you want to choose between soundex, metaphone, or double-metaphone algorithms. Prefer this over edit-distance endpoints (Levenshtein, Jaro-Winkler) when the concern is pronunciation rather than spelling, and over the individual encoding endpoints when you need both tokens encoded and compared in a single call.

## Known failure modes

- Missing required field 'a' or 'b' returns a validation error
- Empty string for either token rejected (minLength: 1)
- String exceeding 256 characters rejected (maxLength: 256)
- Invalid algorithm value (not one of soundex, metaphone, double-metaphone) causes error
- Payment failure via x402 protocol results in 402 response and no computation

## How this service works

Report whether two tokens sound alike under a chosen algorithm (soundex, metaphone or double-metaphone; default double-metaphone). Returns each token's codes and a boolean match.

## Output

Returns each token's phonetic encoding(s) under the chosen algorithm (primary and secondary codes for double-metaphone, single code for soundex/metaphone) and a boolean indicating whether the two tokens are considered phonetically equivalent.

## 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",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "a",
      "b"
     ],
     "properties": {
      "a": {
       "type": "string",
       "maxLength": 256,
       "minLength": 1,
       "description": "First token."
      },
      "b": {
       "type": "string",
       "maxLength": 256,
       "minLength": 1,
       "description": "Second token."
      },
      "algorithm": {
       "enum": [
        "soundex",
        "metaphone",
        "double-metaphone"
       ],
       "type": "string",
       "description": "Encoding to compare with. Default double-metaphone."
      }
     },
     "additionalProperties": false
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/phonetic-similarity-compare-similarity-openverbs-com-e306e7f7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from similarity.openverbs.com](https://www.zero.xyz/host/similarity.openverbs.com/llms.txt)