curl --request POST \
  --url https://api.iotools.cloud/v1/tool/textile-yarn-converter \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "category": "knitting-needle",
  "value": "4.5",
  "needleSystem": "metric"
}
'

{
  "tool": "textile-yarn-converter",
  "tool_version": "1.0.1",
  "outputs": {
    "result": "4.5 mm · US 7 · UK/CA 7 · JP 8",
    "equivalents": [
      {
        "property": "Metric (mm)",
        "value": "4.5 mm"
      },
      {
        "property": "US",
        "value": "7"
      },
      {
        "property": "UK / Canada",
        "value": "7"
      },
      {
        "property": "Japanese",
        "value": "8"
      }
    ]
  },
  "credits_used": 3,
  "credits_remaining": null
}