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US Treasury Par Yield Curve API
x402
US Treasury Par Yield Curve API is a paid API for AI agents from x402.donnyautomation.com, paid per call via x402, $0.03/call, status unknown (last checked 2026-10-01).
Returns the full US Treasury constant-maturity par yield curve for any published business day, including key spreads (2s10s, 3m10y, 5s30s) with explicit yield curve inversion flags.
Price / call$0.03
Success—
StatusUnknown
How this service works
US Treasury par yield curve, every constant maturity from 1 month to 30 years for a published business day. Returns curve[] with tenor, months and percent, spreads (2s10s, 3m10y, 5s30s) and an explicit inversion flag - the real question is whether the curve is inverted, not what fourteen numbers are. A tenor Treasury did not publish is null, never zero. Pass ?latest=1 OR ?date=YYYY-MM-DD, not both. Errors: 400 conflicting_params|bad_latest|bad_date, 404 no_curve with the available range.
Output
A structured JSON object containing all published US Treasury constant-maturity par yield rates from 1-month to 30-year for the requested business day, key spreads (2s10s, 3m10y, 5s30s) pre-computed, an explicit boolean inversion flag per spread, and null (not zero) for any tenor the Treasury did not publish that day. Returns 404 with available date range if a non-publication day is requested.
Example use cases
Real-time yield curve inversion check
“Is the Treasury yield curve currently inverted? Give me the 2s10s and 3m10y spreads and tell me clearly whether each one is in inversion territory right now.”
Historical spread lookup for macro report
“What were the 2s10s, 3m10y, and 5s30s Treasury spreads on March 15, 2023? I need to know if the curve was inverted that day for a macro analysis I'm writing.”
Full CMT rates for risk model input
“Fetch the complete US Treasury constant-maturity yield curve for the most recent published business day — I need all tenors from 1 month to 30 years, with nulls for any that weren't published that day, for my risk model.”
Technical details
Endpoint
GEThttps://x402.donnyautomation.com/treasury?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need official US Treasury CMT rates for macro, rates, credit, or risk workflows and want key curve spreads and inversion flags pre-computed rather than deriving them yourself. Prefer it over scraping Treasury.gov directly when you need structured JSON output, reliable null-vs-zero semantics for missing tenors, or programmatic inversion detection without extra computation.
Side effects
- 404 if requested date is not a Treasury publication day (weekend, holiday, or no data), with available date range returned
- 400 if both 'date' and 'latest=1' are supplied simultaneously
- 400 if date format is invalid or unparseable
- Payment failure (402) if USDC payment is not included or insufficient
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"ts": "2026-08-03T00:00:00.000Z",
"date": "2026-08-03",
"curve": [
{
"tenor": "3 Mo",
"months": 3,
"percent": 3.91
},
{
"tenor": "2 Yr",
"months": 24,
"percent": 4.25
},
{
"tenor": "10 Yr",
"months": 120,
"percent": 4.7
}
],
"spreads": {
"unit": "percentage points",
"2s10s": 0.45,
"3m10y": 0.79,
"5s30s": 0.83
},
"isLatest": true,
"inversion": {
"2s10s": false,
"3m10y": false,
"anyInverted": false
},
"attribution": "Daily Treasury Par Yield Curve Rates, U.S. Department of the Treasury (public domain)."
}
}Tags
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