A US 30-year Treasury yield API returns one tenor, not the full curve. On Bonds-API the key is US_30Y. Call GET https://bonds-api.com/api/v1/latest?countries=US&maturities=30Y with query api_key (not Bearer).
Starter is $19/mo (1,000 requests) with a 7-day trial. This is not Fed Funds / SOFR. MCP: mcp.bonds-api.com. Docs: bonds-api.com/docs.
Request: latest US 30Y
curl "https://bonds-api.com/api/v1/latest?countries=US&maturities=30Y&api_key=YOUR_API_KEY"Sibling: official US curve (2026-04-14)
Latest does not publish a frozen 30Y tick in the docs. The curve fixture on that date prints 30Y 4.55:
{
"success": true,
"data": {
"country": "US",
"date": "2026-04-14",
"curve": [
{"maturity": "3M", "yield": 4.30},
{"maturity": "30Y", "yield": 4.55}
],
"spread_2y_10y": 45.0,
"inverted": false
}
}Copy the latest curl for today’s US_30Y. The same curve also lists 2Y 3.80, 5Y 4.05, and 10Y 4.25.
Go live
1. Register — 7-day trial.
2. Copy api_key.
3. GET latest with maturities=30Y.
4. Render US_30Y. Use /curve when you need 3M–30Y together.