US Debt Composition API
What the US national debt is actually made of, served from the Treasury's Monthly Statement of the Public Debt. The headline debt-to-the-penny figure is one number; this is the breakdown — how the roughly $39 trillion splits across Treasury Bills, Notes, Bonds, TIPS and Floating-Rate Notes (the marketable, tradable debt) versus the non-marketable debt (the Government Account Series held by federal trust funds, Savings Bonds, and State and Local Government Series). The composition endpoint returns the latest full breakdown by security class, each with its share of the total and its split between debt held by the public and intragovernmental holdings. The marketable endpoint isolates the tradable securities (Bills/Notes/Bonds/TIPS/FRN) with each one's share of marketable debt — the issuance mix that rates traders and the Treasury's quarterly refunding watch. The history endpoint returns one security class's outstanding amount month by month. This is the debt-structure data-cut, distinct from the debt-to-the-penny total, the fiscal-deficit and the yield-curve APIs in the catalogue. Live, updated monthly, no key on the upstream, nothing stored.
api.oanor.com/debtcomposition-api
