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Interest rates API

Access UK government yield curves through REST or MCP. Request the latest accepted value, an exact period or dated history.

First request

Quickstart →

curl --request GET \
  --url "https://api.narwhalapi.com/v1/economics/GBR/yield-curve?date=2026-09-10&maturity=2y%2C10y" \
  --header "Authorization: Bearer $NARWHAL_API_KEY"

Example response Saved source sample · not a live request

{
  "country": "GBR",
  "curve_type": "nominal_zero_coupon",
  "date": "2026-09-10",
  "yields": [
    {
      "maturity": "2y",
      "yield_percent": "4.6509003413966044"
    },
    {
      "maturity": "10y",
      "yield_percent": "5.3572243604351168"
    }
  ]
}

Endpoints

GETUK and US yield curves/v1/economics/{country}/yield-curve

country: Use GBR for the Bank of England curve or USA for the US Treasury curve.
date: Omit for the latest admitted observation. A supplied value selects that exact period; unavailable periods return 404.
version_id: Optional immutable publication version. Omit to read the current admitted curve.
maturity: Optional on both routes. Omit for the whole available curve. Allowed: 0.5y, 1y, 1.5y, 2y, 2.5y, 3y, 3.5y, 4y, 4.5y, 5y, 5.5y, 6y, 6.5y, 7y, 7.5y, 8y, 8.5y, 9y, 9.5y, 10y, 10.5y, 11y, 11.5y, 12y, 12.5y, 13y, 13.5y, 14y, 14.5y, 15y, 15.5y, 16y, 16.5y, 17y, 17.5y, 18y, 18.5y, 19y, 19.5y, 20y, 20.5y, 21y, 21.5y, 22y, 22.5y, 23y, 23.5y, 24y, 24.5y, 25y, 25.5y, 26y, 26.5y, 27y, 27.5y, 28y, 28.5y, 29y, 29.5y, 30y, 30.5y, 31y, 31.5y, 32y, 32.5y, 33y, 33.5y, 34y, 34.5y, 35y, 35.5y, 36y, 36.5y, 37y, 37.5y, 38y, 38.5y, 39y, 39.5y, 40y. For USA use: 1m, 1.5m, 2m, 3m, 4m, 6m, 1y, 2y, 3y, 5y, 7y, 10y, 20y, 30y. Duplicates are removed and terms sorted; unsupported labels return 400.

MCP · economics_get_yield_curve

API reference →

GETUK and US yield curves history/v1/economics/{country}/yield-curve/history

country: Use GBR for the Bank of England curve or USA for the US Treasury curve.
start: Inclusive lower bound. Omit for the first available period.
end: Inclusive upper bound; cannot precede start. Omit for the last available period.
limit: Default 100. Counts dates or years, not individual yield points.
cursor: Pass next_cursor unchanged with the same country, filters and limit. Cursors expire after 24 hours.
maturity: Optional on both routes. Omit for the whole available curve. Allowed: 0.5y, 1y, 1.5y, 2y, 2.5y, 3y, 3.5y, 4y, 4.5y, 5y, 5.5y, 6y, 6.5y, 7y, 7.5y, 8y, 8.5y, 9y, 9.5y, 10y, 10.5y, 11y, 11.5y, 12y, 12.5y, 13y, 13.5y, 14y, 14.5y, 15y, 15.5y, 16y, 16.5y, 17y, 17.5y, 18y, 18.5y, 19y, 19.5y, 20y, 20.5y, 21y, 21.5y, 22y, 22.5y, 23y, 23.5y, 24y, 24.5y, 25y, 25.5y, 26y, 26.5y, 27y, 27.5y, 28y, 28.5y, 29y, 29.5y, 30y, 30.5y, 31y, 31.5y, 32y, 32.5y, 33y, 33.5y, 34y, 34.5y, 35y, 35.5y, 36y, 36.5y, 37y, 37.5y, 38y, 38.5y, 39y, 39.5y, 40y. For USA use: 1m, 1.5m, 2m, 3m, 4m, 6m, 1y, 2y, 3y, 5y, 7y, 10y, 20y, 30y. Duplicates are removed and terms sorted; unsupported labels return 400.