{
  "x402Version": 2,
  "id": 3201,
  "slug": "3201",
  "resource": "https://mortgage-amortization.underscoredone.com/calculate",
  "description": "Give this API a loan amount, an interest rate, and a repayment term, and it returns the exact monthly payment plus a full month-by-month schedule: interest paid, principal repaid, and balance remaining for every payment. Ask what an extra $300 a month, or a $10,000 lump sum in month 24, would do and it reports the months and interest saved. Every figure uses banker's rounding at pinned precision, so two correct systems agree to the cent. You supply the rate; the API does the math.",
  "type": "http",
  "accepts": [
    {
      "scheme": "exact",
      "network": "eip155:8453",
      "payTo": "0xE9740820225B3918b4ddd1292C7cA4Ca0e2C2F08",
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "amount": "10000",
      "maxTimeoutSeconds": 300
    },
    {
      "scheme": "exact",
      "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
      "payTo": "8ugAWAXDB8V18kiUrGZTq1oMvU3C6Fxs8hfC6rvzQT3b",
      "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
      "amount": "10000",
      "maxTimeoutSeconds": 300
    }
  ],
  "outputSchema": {
    "bazaar": {
      "info": {
        "input": {
          "body": {
            "annual_rate_percent": 6.5,
            "extra_monthly_payment": 300,
            "one_time_payments": [
              {
                "amount": 10000,
                "month": 24
              }
            ],
            "principal": 400000,
            "rounding": 2,
            "start_date": "2026-07-01",
            "summary_only": false,
            "term_months": 360
          },
          "bodyType": "json",
          "method": "POST",
          "type": "http"
        },
        "output": {
          "example": {
            "api_version": "1.0.0",
            "inputs_echo": {
              "annual_rate_percent": 6.5,
              "principal": 400000,
              "start_date": "2026-07-01",
              "term_months": 360
            },
            "rounding": {
              "decimals": 2,
              "final_payment_adjusted": true,
              "mode": "half_even"
            },
            "schedule": [
              {
                "balance": 399338.4,
                "date": "2026-07-01",
                "extra_applied": 300,
                "interest": 2166.67,
                "payment": 2828.27,
                "payment_number": 1,
                "principal": 661.6,
                "scheduled_payment": 2528.27
              }
            ],
            "scheduled_payment": 2528.27,
            "summary": {
              "final_payment": 2530.88,
              "payoff_date": "2056-06-01",
              "scheduled_term_months": 360,
              "total_interest": 510179.81,
              "total_paid": 910179.81
            },
            "with_extra_payments": {
              "actual_term_months": 257,
              "final_payment": 200.36,
              "interest_saved": 175942.33,
              "months_saved": 103,
              "payoff_date": "2047-11-01",
              "total_interest": 334237.48,
              "total_paid": 734237.48
            }
          },
          "type": "json"
        }
      },
      "schema": {
        "$schema": "https://json-schema.org/draft/2020-12/schema",
        "properties": {
          "input": {
            "additionalProperties": false,
            "properties": {
              "body": {
                "additionalProperties": false,
                "properties": {
                  "annual_rate_percent": {
                    "description": "Yearly interest rate as a percentage - send 6.5 for 6.5%. Use 0 for an interest-free loan.",
                    "type": "number"
                  },
                  "extra_monthly_payment": {
                    "description": "Optional extra principal paid every month. Defaults to 0.",
                    "type": "number"
                  },
                  "one_time_payments": {
                    "description": "Optional lump-sum principal payments; each item needs 'month' and 'amount'.",
                    "type": "array"
                  },
                  "principal": {
                    "description": "Amount borrowed, in dollars. Must be greater than zero.",
                    "type": "number"
                  },
                  "rounding": {
                    "description": "Decimal places for money values, 2 to 6. Defaults to 2.",
                    "type": "integer"
                  },
                  "start_date": {
                    "description": "Date of the first payment, YYYY-MM-DD.",
                    "type": "string"
                  },
                  "summary_only": {
                    "description": "Set true to return totals only, without the row-by-row schedule.",
                    "type": "boolean"
                  },
                  "term_months": {
                    "description": "Number of monthly payments. 360 for a 30-year mortgage. Minimum 1.",
                    "type": "integer"
                  }
                },
                "required": [
                  "principal",
                  "annual_rate_percent",
                  "term_months",
                  "start_date"
                ],
                "type": "object"
              },
              "bodyType": {
                "enum": [
                  "json",
                  "form-data",
                  "text"
                ],
                "type": "string"
              },
              "method": {
                "enum": [
                  "POST",
                  "PUT",
                  "PATCH"
                ],
                "type": "string"
              },
              "type": {
                "const": "http",
                "type": "string"
              }
            },
            "required": [
              "type",
              "method",
              "bodyType",
              "body"
            ],
            "type": "object"
          },
          "output": {
            "properties": {
              "example": {
                "properties": {
                  "api_version": {
                    "type": "string"
                  },
                  "inputs_echo": {
                    "additionalProperties": true,
                    "type": "object"
                  },
                  "rounding": {
                    "additionalProperties": true,
                    "type": "object"
                  },
                  "schedule": {
                    "items": {
                      "type": "object"
                    },
                    "type": "array"
                  },
                  "scheduled_payment": {
                    "type": "number"
                  },
                  "summary": {
                    "additionalProperties": true,
                    "type": "object"
                  },
                  "with_extra_payments": {
                    "additionalProperties": true,
                    "type": "object"
                  }
                },
                "required": [
                  "api_version",
                  "inputs_echo",
                  "rounding",
                  "scheduled_payment",
                  "summary",
                  "with_extra_payments",
                  "schedule"
                ],
                "type": "object"
              },
              "type": {
                "type": "string"
              }
            },
            "required": [
              "type"
            ],
            "type": "object"
          }
        },
        "required": [
          "input"
        ],
        "type": "object"
      }
    }
  },
  "tags": [
    "bazaar"
  ],
  "sourceHost": "mortgage-amortization.underscoredone.com",
  "lastUpdated": "2026-09-14T19:47:53.09Z",
  "quality": {
    "calls30d": 5,
    "uniquePayers30d": 4,
    "lastCalledAt": "2026-09-14T19:47:52.669Z"
  },
  "liveness": {},
  "verified": false,
  "featured": false,
  "provider": {
    "host": "mortgage-amortization.underscoredone.com",
    "manifest_name": "mortgage-amortization.underscoredone.com",
    "source": "cdp-mirror",
    "source_manifest_url": "https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources",
    "submitted_at": "2026-09-18T22:00:31.484Z"
  }
}