curl --request POST \
  --url https://api.iotools.cloud/v1/tool/pkce-code-verifier-challenge-generator \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "verifierLength": "64",
  "challengeMethod": "S256",
  "verifierCharset": "unreserved",
  "verifierOverride": "dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk"
}
'

{
  "tool": "pkce-code-verifier-challenge-generator",
  "tool_version": "1.0.1",
  "outputs": {
    "codeVerifier": "dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk",
    "codeChallenge": "E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM",
    "codeChallengeMethod": "S256",
    "pkceBreakdown": [
      {
        "step": "1. code_verifier",
        "value": "dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk"
      },
      {
        "step": "   generated via",
        "value": "provided override (not randomly generated)"
      },
      {
        "step": "   length",
        "value": "43 characters"
      },
      {
        "step": "2. code_challenge",
        "value": "base64url(SHA-256(code_verifier)) = E9Melhoa2OwvFrEMTJguCHaoeK1t8URWbuGJSstw-cM"
      },
      {
        "step": "3. code_challenge_method",
        "value": "S256"
      }
    ]
  },
  "credits_used": 3,
  "credits_remaining": null
}