curl --request POST \
  --url https://api.iotools.cloud/v1/tool/hreflang-generator \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "pairs": "en-US, https://example.com/\nen-GB, https://example.com/uk/\nfr, https://example.com/fr/\nde, https://example.com/de/",
  "xDefault": "https://example.com/",
  "format": "html",
  "normalize": "true"
}
'

{
  "tool": "hreflang-generator",
  "tool_version": "1.0.1",
  "outputs": {
    "tags": "<link rel=\"alternate\" hreflang=\"en-US\" href=\"https://example.com/\" />\n<link rel=\"alternate\" hreflang=\"en-GB\" href=\"https://example.com/uk/\" />\n<link rel=\"alternate\" hreflang=\"fr\" href=\"https://example.com/fr/\" />\n<link rel=\"alternate\" hreflang=\"de\" href=\"https://example.com/de/\" />\n<link rel=\"alternate\" hreflang=\"x-default\" href=\"https://example.com/\" />",
    "issues": "Reminder: every URL listed here must serve the same block back, including a self-referencing tag. hreflang without return links is ignored."
  },
  "credits_used": 3,
  "credits_remaining": null
}