Treasury Yields API - US Yield Curve, Daily Rates, History

Problem: your fintech dashboard, mortgage or loan calculator, bond tool or AI agent needs today's US Treasury yields, the 10Y-2Y spread or the yield curve on a past date. Treasury publishes the numbers as one HTML/CSV page per year with columns that change over time (no 1-month bill before 2001, 4-month since 2022, 1.5-month since 2025), and it is often slow to load.

This API: one JSON call, no API key, answers from a maintained copy of the official files.

• Curves: nominal par yield curve 1M to 30Y (since 1990), real yield curve / TIPS 5Y-30Y (since 2003), T-bill rates (bank discount and coupon equivalent, since 2002), long-term composite and 20Y CMT (since 2000).
• Spreads: 10Y-2Y, 10Y-3M, 30Y-5Y, 2Y-3M in percentage points, plus inverted10y2y / inverted10y3m flags.
• Change: change1d = basis-point change of every maturity versus the previous business day.
• Modes: latest, date (a holiday or weekend returns the previous business day and keeps requestedDate), history (daily, weekly or monthly), spreads, and inversion = every period when 10Y-2Y or 10Y-3M was below zero, with start, end, length and the deepest point.
• Source: U.S. Department of the Treasury daily interest rate data (public domain). Every row carries source and sourceUrl.

Example (API)

curl -X POST "https://api.apify.com/v2/acts/martin10291~treasury-yields-api/run-sync-get-dataset-items?token=YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"mode": "latest"}'

Output row (measured 2026-11-13):

{"date": "2026-11-12", "curve": "nominal",
 "yields": {"1M": 4.12, "3M": 4.32, "6M": 4.42, "1Y": 4.65, "2Y": 4.86, "5Y": 4.95, "10Y": 5.1, "20Y": 5.48, "30Y": 5.43},
 "spreads": {"10Y-2Y": 0.24, "10Y-3M": 0.78, "30Y-5Y": 0.48, "2Y-3M": 0.54},
 "inverted10y2y": false, "inverted10y3m": false,
 "change1d": {"2Y": 13, "10Y": 12, "30Y": 8},
 "source": "U.S. Treasury, Daily Treasury Par Yield Curve Rates", "unit": "percent"}

Inversion periods 2022-2024 ({"mode": "inversion", "startDate": "2022-01-01", "endDate": "2024-12-31"}):

{"spread": "10Y-2Y", "start": "2022-07-06", "end": "2024-08-26", "days": 783, "tradingDays": 537, "minSpread": -1.08, "minSpreadDate": "2023-07-03"}

More inputs:

• {"mode": "date", "date": "2026-11-11"} -> curve of 2026-11-10 (11-11 was a federal holiday), requestedDate kept.
• {"mode": "history", "startDate": "2020-01-01", "endDate": "2026-11-12", "maturities": ["2Y", "10Y"], "frequency": "monthly"}
• {"mode": "latest", "curve": "real"} -> TIPS real yields.

Use from agents (MCP)

Add the Apify MCP server (https://mcp.apify.com?tools=martin10291/treasury-yields-api) to Claude, Cursor or any MCP client and ask: "What is the 10Y-2Y Treasury spread today and how did it change this month?".

Schedule it

Set onlyNew: true and a monitorId, schedule the actor once per business day (after 18:00 New York time): each run returns only the new Treasury business days since the last run.

Input

Field	Meaning
mode	latest (default), date, history, spreads, inversion
curve	nominal (default), real, bills, longterm
date	YYYY-MM-DD for mode date
startDate, endDate	range for history / spreads / inversion (default last 30 days, max 40 years)
maturities	optional filter, e.g. ["3M","2Y","10Y"]
frequency	daily, weekly (last business day of the week), monthly
limit	max rows, default 1000 (newest kept)
onlyNew, monitorId	return only new business days per watch

Honest limits

• Treasury publishes once per business day (usually 15:30-18:00 New York time); there is no intraday data.
• Values are exactly as published (percent, 2 decimals). Columns that did not exist in a year (e.g. 1M before 2001, 20Y in 1987-1993, 30Y in 2002-2006) are null, never invented.
• Spreads and inversions are computed on the nominal curve only.
• A cold history call on Apify may take up to ~20 s per uncached year because the Treasury files load slowly; marketplace calls (RapidAPI, API.market) answer from our cache in milliseconds.

FAQ

Is this an official Treasury product? No. It republishes official U.S. Treasury data, which is public domain; the source page is in every row. Do I need a key? Only your Apify token (or the marketplace key on RapidAPI / API.market).