Word frequency & rarity gauge API

How common is a word? Returns Google-Books corpus frequency (occurrences per million), a derived Zipf score (log10 per-billion), syllable count, and a human rarity band (very-common…very-rare). Answers 'is this word rare?', 'what's the Zipf frequency of serendipity?'.

Price$0.01per request

MethodPOST

Route/v1/words/frequency

StatusLive

MIME typeapplication/json

Rate limit60/minute

Cache604800s public

wordsfrequencyrarityzipfcorpusreadabilitydatamuselexical

API URLhttps://x402.hexl.dev/v1/words/frequency

Integration docs

Example request

{
  "word": "serendipity"
}

Example response

{
  "word": "serendipity",
  "found": true,
  "frequencyPerMillion": 0.292473,
  "zipf": 2.47,
  "band": "uncommon",
  "syllables": 5
}

Input schema

{
  "type": "object",
  "required": [
    "word"
  ],
  "properties": {
    "word": {
      "type": "string"
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}