# US Treasury Par Yield Curve API

> US Treasury Par Yield Curve API is a paid API for AI agents from api.vextorium.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-12).

Returns the latest US Treasury par yield curve rates (1 month to 30 years) with basis-point changes versus N days ago, plus 10y-2y and 10y-3m spreads and inversion flag.

## Facts

- Endpoint: POST https://api.vextorium.com/curva-tesoro-eeuu-pago?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/us-treasury-par-yield-curve-api-cb9ea622
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5INvAS1KUpwfawkQNK1CO

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability us-treasury-par-yield-curve-api-cb9ea622 -d '<json body>'
```

Example prompt: Pull the latest US Treasury par yield curve with rates across all maturities and tell me how yields have shifted versus 60 days ago, including whether the 10y-2y spread is showing an inversion.

## When to prefer this

Choose this endpoint when you need authoritative, official US Treasury par yield curve data with built-in spread calculations and inversion detection — especially useful for macro analysis, fixed income monitoring, or any workflow that needs to track yield curve shape changes over time without building your own data pipeline from Treasury.gov.

## Known failure modes

- Treasury data not yet published for today (data may lag by one business day)
- dias_comparar out of range (must be 1-365)
- Upstream Treasury website unavailable or rate-limited
- Weekend/holiday dates may return last available business day data
- No historical data available for the requested comparison date

## How this service works

Latest US Treasury par yield curve (1 month to 30 years), change in basis points versus N days ago, 10y-2y and 10y-3m spreads and inversion flag. Official US Treasury data (public domain).

## Output

Returns a JSON object with: an array of maturity buckets (1 Mo through 30 Yr) each containing the current par yield (%) and change in basis points vs the comparison date; the data date; the comparison date; the source label; the 10y-2y spread in basis points; the 10y-3m spread in basis points; and a boolean flag indicating whether the 10y-2y portion of the curve is inverted.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "required": [],
     "properties": {
      "dias_comparar": {
       "type": "integer",
       "description": "Compare with N days earlier (1-365, default 30)"
      }
     }
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": [
      "object",
      "null"
     ],
     "properties": {
      "curva": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": [
         "null",
         "object"
        ],
        "properties": {
         "plazo": {
          "type": [
           "null",
           "string"
          ]
         },
         "tipo_pct": {
          "type": [
           "null",
           "number"
          ]
         },
         "cambio_pb": {
          "type": [
           "null",
           "number"
          ]
         }
        }
       }
      },
      "fecha": {
       "type": [
        "string",
        "null"
       ]
      },
      "fuente": {
       "type": [
        "string",
        "null"
       ]
      },
      "comparado_con": {
       "type": [
        "string",
        "null"
       ]
      },
      "invertida_2a_10a": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "diferencial_10a_2a_pb": {
       "type": [
        "number",
        "null"
       ]
      },
      "diferencial_10a_3m_pb": {
       "type": [
        "number",
        "null"
       ]
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "curva": [
   {
    "plazo": "1 Mo",
    "tipo_pct": 4.06,
    "cambio_pb": 21
   },
   {
    "plazo": "1.5 Month",
    "tipo_pct": 4.1,
    "cambio_pb": 22
   },
   {
    "plazo": "2 Mo",
    "tipo_pct": 4.13,
    "cambio_pb": 24
   },
   {
    "plazo": "3 Mo",
    "tipo_pct": 4.17,
    "cambio_pb": 25
   },
   {
    "plazo": "4 Mo",
    "tipo_pct": 4.26,
    "cambio_pb": 29
   },
   {
    "plazo": "6 Mo",
    "tipo_pct": 4.27,
    "cambio_pb": 27
   },
   {
    "plazo": "1 Yr",
    "tipo_pct": 4.44,
    "cambio_pb": 26
   },
   {
    "plazo": "2 Yr",
    "tipo_pct": 4.78,
    "cambio_pb": 39
   },
   {
    "plazo": "3 Yr",
    "tipo_pct": 4.91,
    "cambio_pb": 45
   },
   {
    "plazo": "5 Yr",
    "tipo_pct": 5.01,
    "cambio_pb": 46
   },
   {
    "plazo": "7 Yr",
    "tipo_pct": 5.12,
    "cambio_pb": 46
   },
   {
    "plazo": "10 Yr",
    "tipo_pct": 5.24,
    "cambio_pb": 45
   },
   {
    "plazo": "20 Yr",
    "tipo_pct": 5.64,
    "cambio_pb": 37
   },
   {
    "plazo": "30 Yr",
    "tipo_pct": 5.61,
    "cambio_pb": 34
   }
  ],
  "fecha": "2026-10-01",
  "fuente": "U.S. Department of the Treasury, Daily Treasury Par Yield Curve Rates (dominio público)",
  "comparado_con": "2026-09-01",
  "invertida_2a_10a": false,
  "diferencial_10a_2a_pb": 46,
  "diferencial_10a_3m_pb": 107
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/us-treasury-par-yield-curve-api-cb9ea622/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.vextorium.com](https://www.zero.xyz/host/api.vextorium.com/llms.txt)