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Treasury Yield API

The Treasury Yield API provides the current and historical U.S. Treasury yield curve: nominal Constant Maturity Treasury (CMT) par yields for 14 maturities (1 month to 30 years), the real (inflation-indexed / TIPS) yield curve, and Treasury bill rates. The par response also includes precomputed spreads (2s10s, 3m10s, 5s30s) and a yield-curve inversion flag.

Data is sourced from the U.S. Department of the Treasury and updated every business day.

Available endpoints:

Treasury yields by maturity:

1 Month · 1.5 Month · 2 Month · 3 Month · 4 Month · 6 Month · 1 Year · 2 Year · 3 Year · 5 Year · 7 Year · 10 Year · 20 Year · 30 Year

(4.1)

From 4,458 users

2,900+

Applications using this API

API Status

Online - All Systems Operational

API Response Times

Average
P50
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P95
344ms376ms387ms753ms998ms

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/v1/treasuryyield GET

https://api.api-ninjas.com/v1/treasuryyield

Returns the latest yield curve for the requested type. The current curve is free; a specific historical date and the combined type=all response require a premium subscription.

Parameters

  • type  optional

    Which curve to return. Must be one of the following values (defaults to par):

    parNominal Constant Maturity Treasury (CMT) yield curve. Default.
    realReal (inflation-indexed / TIPS) yield curve.
    billTreasury bill rates.
    allAll three curves combined in one response. Premium only.
  • date  optional

    Business day to retrieve (YYYY-MM-DD). Defaults to the latest. Dates beyond the free window are premium.

  • format  optional

    Response format: json (default) or csv.

Headers

  • X-Api-Key  required

    API Key associated with your account.

Response

A JSON object with the following fields:

  • date

    The business day of the curve (YYYY-MM-DD).

  • type

    The curve type returned: par, real, or bill.

  • rates

    An object mapping each maturity to its yield percent. A maturity not published on a given day is null. For bill, each value is an object with coupon_equivalent and discount_rate. The available maturity keys depend on type (these are also the values accepted by the maturity parameter on /v1/treasuryyieldhistorical):

    par: month_1month_1_5month_2month_3month_4month_6year_1year_2year_3year_5year_7year_10year_20year_30

    real: year_5year_7year_10year_20year_30

    bill: week_4week_6week_8week_13week_17week_26week_52

  • spread_2y10y

    10-year minus 2-year yield. Returned for par only.

  • spread_3m10y

    10-year minus 3-month yield. Returned for par only.

  • spread_5y30y

    30-year minus 5-year yield. Returned for par only.

  • curve_inverted

    Whether the 2s10s spread is negative (10-year below 2-year). Returned for par only.

Sample Request Live Demo!

type
date

Try our APIs in the API playground

Sign up for a free API key to get started — no credit card required.

https://api.api-ninjas.com/v1/treasuryyield?type=par

Headers

X-Api-KeyLog in or sign up to get your API Key

Sample Response

JSON
{
    date:"2026-08-10",
    type:"par",
    rates:{
      month_1:3.79,
      month_1_5:3.8,
      month_2:3.84,
      month_3:3.89,
      month_4:3.91,
      month_6:4,
      year_1:4.04,
      year_2:4.25,
      year_3:4.31,
      year_5:4.41,
      year_7:4.56,
      year_10:4.72,
      year_20:5.25,
      year_30:5.25
    },
    spread_2y10y:0.47,
    spread_3m10y:0.83,
    spread_5y30y:0.84,
    curve_inverted:false
}

Code Examples

1 2 curl -X GET "https://api.api-ninjas.com/v1/treasuryyield?type=par" \ -H "X-Api-Key: YOUR_API_KEY"

/v1/treasuryyieldhistorical GETPremium only

https://api.api-ninjas.com/v1/treasuryyieldhistorical

Returns a historical time series for a single maturity. Omit maturity to get the full curve per date. This endpoint requires a premium subscription.

Parameters

  • type  optional

    par (default), real, or bill.

  • maturity  optional

    A single maturity code (e.g. year_10, week_13). Omit for full-curve history (premium).

    Maturity codes ▶
  • start_date  optional

    Start of the range (YYYY-MM-DD).

  • end_date  optional

    End of the range (YYYY-MM-DD).

  • format  optional

    json (default) or csv. Premium bulk responses include a next cursor passed back via the page parameter.

Response

A JSON object with the following fields:

  • type

    The curve type: par, real, or bill.

  • maturity

    The maturity code returned. Present for a single maturity; omitted in full-curve mode.

  • data

    An array of time-series points, oldest first. For a single maturity each item is { date, rate_pct } (bills also include discount_rate). In full-curve mode each item is { date, rates }, where rates maps each maturity to its yield percent.

  • next

    A pagination cursor for the next page of bulk results, or null. Pass it back as the page parameter.

Sample Request Live Demo!

type
maturity
start_date
end_date

Try our APIs in the API playground

Sign up for a free API key to get started — no credit card required.

https://api.api-ninjas.com/v1/treasuryyieldhistorical?type=par&maturity=year_10

Headers

X-Api-KeyLog in or sign up to get your API Key

Sample Response

JSON
{
    type:"par",
    maturity:"year_10",
    data:[
      {
        date:"2026-08-05",
        rate_pct:4.7
      },
      {
        date:"2026-08-06",
        rate_pct:4.69
      },
      {
        date:"2026-08-07",
        rate_pct:4.65
      },
      {
        date:"2026-08-10",
        rate_pct:4.72
      }
    ]
}

Frequently Asked Questions

  • Yes, but you must have a premium subscription. Commercial use of the Treasury Yield API is not permitted on the free tier. See our pricing page to choose a plan that fits your needs.
  • Sign up for a free account to instantly get your API key, then pass it in the X-Api-Key header on every request. The documentation above includes ready-to-run examples in cURL, Python, JavaScript, Node.js, and more.
  • Your API requests will simply be denied once you hit your monthly quota — you will never be charged more than the plan you signed up for. To increase your quota, you can upgrade your plan any time on our pricing page.
  • The API responds with a standard HTTP status code and a JSON error message describing the problem. See our error codes reference for the full list of codes and how to resolve each one, or contact support if you need help.