# US Treasury Par Yield Curve API

> US Treasury Par Yield Curve API is a paid API for AI agents from treasury-yield-curve.x402supply.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-17).

Returns the US Treasury par yield curve rates (1-month to 30-year maturities, in percent) for a specified date or the latest available trading day

## Facts

- Endpoint: POST https://treasury-yield-curve.x402supply.com/tools/yield_curve?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-17
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/us-treasury-par-yield-curve-api-31fddfb7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Y0hBOhyabWgRYsLxyHPM6

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-31fddfb7 -d '<json body>'
```

Example prompt: What does the US Treasury par yield curve look like today — give me the rates from 1-month all the way out to 30 years?

## When to prefer this

Choose this endpoint when you need official US Treasury par yield curve rates across all standard maturities for any date since January 2, 1990. It is the authoritative source for risk-free rate data, yield curve shape analysis, and fixed-income benchmarking. Prefer it over scraped or third-party rate aggregators when data provenance from the US Treasury matters. It handles non-trading days gracefully by returning the prior business day, making it robust for automated pipelines.

## Known failure modes

- Date before 1990-01-02 returns an error (data not available that early)
- Future dates are rejected with a validation error
- Non-trading days return prior business day data with an explanatory note
- Malformed date strings (not YYYY-MM-DD) return a validation error
- Specific maturities may be missing for very old dates if not yet issued

## How this service works

US Treasury par yield curve (1mo to 30yr, percent) for one date, or the latest if omitted. Weekend or holiday dates return the nearest prior business day with a note. Data from U.S. Treasury; not financial advice.

## Output

A set of US Treasury par yield curve rates in percent for each standard maturity (1-month, 2-month, 3-month, 6-month, 1-year, 2-year, 3-year, 5-year, 7-year, 10-year, 20-year, 30-year) for the requested date. If the requested date falls on a weekend or holiday, the response returns data for the nearest prior business day and includes a note indicating this adjustment. Data is sourced from the US Treasury.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "date": {
   "type": "string",
   "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
   "description": "YYYY-MM-DD, 1990-01-02 or later, not in the future. Omit for the latest curve"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "asOf": "2026-10-09T17:48:01.778Z",
  "date": "2026-10-02",
  "note": "No Treasury curve is published for 2026-10-04 (weekend or market holiday). Returning the nearest prior business day, 2026-10-02.",
  "unit": "percent",
  "source": [
   "https://home.treasury.gov/resource-center/data-chart-center/interest-rates/pages/xml?data=daily_treasury_yield_curve&field_tdr_date_value_month=202610"
  ],
  "yields": {
   "1mo": 4.04,
   "1yr": 4.46,
   "2mo": 4.11,
   "2yr": 4.83,
   "3mo": 4.19,
   "3yr": 4.96,
   "4mo": 4.26,
   "5yr": 5.06,
   "6mo": 4.27,
   "7yr": 5.17,
   "10yr": 5.28,
   "20yr": 5.67,
   "30yr": 5.63,
   "1.5mo": 4.09
  },
  "exactMatch": false,
  "requestedDate": "2026-10-04"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/us-treasury-par-yield-curve-api-31fddfb7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from treasury-yield-curve.x402supply.com](https://www.zero.xyz/host/treasury-yield-curve.x402supply.com/llms.txt)