curl --request POST \
  --url https://api.iotools.cloud/v1/tool/ph-calculator \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "given": "ph",
  "phValue": "7",
  "pohValue": "7",
  "hValue": "0.0000001",
  "ohValue": "0.0000001"
}
'

{
  "tool": "ph-calculator",
  "tool_version": "1.0.2",
  "outputs": {
    "result": [
      {
        "metric": "pH",
        "value": "7"
      },
      {
        "metric": "pOH",
        "value": "7"
      },
      {
        "metric": "[H+] (mol/L)",
        "value": "1.000000e-7"
      },
      {
        "metric": "[OH-] (mol/L)",
        "value": "1.000000e-7"
      },
      {
        "metric": "Classification",
        "value": "Neutral"
      }
    ],
    "steps": "At 25°C: pH + pOH = 14, [H+] × [OH-] = Kw = 1.0×10⁻¹⁴ mol²/L²\npOH = 14 − 7 = 7\n[H+] = 10^(−7) = 1.000000e-7 mol/L\n[OH-] = Kw ÷ [H+] = 1.0×10⁻¹⁴ ÷ 1.000000e-7 = 1.000000e-7 mol/L"
  },
  "credits_used": 5,
  "credits_remaining": null
}