const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({subscription_ids: ['sub_01h04vsc0qhwtsbsxh3422wjs4']})
};

fetch('https://api.paddle.com/customers/{customer_id}/portal-sessions', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{
  "data": {
    "id": "cpls_01h4ge9r64c22exjsx0fy8b48b",
    "customer_id": "ctm_01gysfvfy7vqhpzkq8rjmrq7an",
    "urls": {
      "general": {
        "overview": "https://customer-portal.paddle.com/cpl_01j7zbyqs3vah3aafp4jf62qaw?action=overview&token=pga_eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJjdG1fMDFncm5uNHp0YTVhMW1mMDJqanplN3kyeXMiLCJuYW1lIjoiSm9obiBEb2UiLCJpYXQiOjE3Mjc2NzkyMzh9._oO12IejzdKmyKTwb7BLjmiILkx4_cSyGjXraOBUI_g"
      },
      "subscriptions": [
        {
          "id": "sub_01h04vsc0qhwtsbsxh3422wjs4",
          "cancel_subscription": "https://customer-portal.paddle.com/cpl_01j7zbyqs3vah3aafp4jf62qaw?action=cancel_subscription&subscription_id=sub_01h04vsc0qhwtsbsxh3422wjs4&token=pga_eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJjdG1fMDFncm5uNHp0YTVhMW1mMDJqanplN3kyeXMiLCJuYW1lIjoiSm9obiBEb2UiLCJpYXQiOjE3Mjc2NzkyMzh9._oO12IejzdKmyKTwb7BLjmiILkx4_cSyGjXraOBUI_g",
          "update_subscription_payment_method": "https://customer-portal.paddle.com/cpl_01j7zbyqs3vah3aafp4jf62qaw?action=update_subscription_payment_method&subscription_id=sub_01h04vsc0qhwtsbsxh3422wjs4&token=pga_eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJjdG1fMDFncm5uNHp0YTVhMW1mMDJqanplN3kyeXMiLCJuYW1lIjoiSm9obiBEb2UiLCJpYXQiOjE3Mjc2NzkyMzh9._oO12IejzdKmyKTwb7BLjmiILkx4_cSyGjXraOBUI_g"
        }
      ]
    },
    "created_at": "2024-10-25T06:53:58Z"
  },
  "meta": {
    "request_id": "fa176777-4bca-49ec-aa1e-f53885333cb7"
  }
}