US National Debt API — to the penny, back to 1790

What you get

Endpoints

All paths relative to your gateway base URL. Auth: X-Api-Key header. Every 200 ships ETag, Cache-Control and RateLimit-* headers.

Free+ = included from the free plan up. Every endpoint and the full history are on every plan — paid tiers raise your monthly volume (500 → 50,000 → 500,000 → 5,000,000 req/mo). Compare plans.

Endpoint reference

Parameters, response fields, and real sample responses — including the error shapes, so you can code the unhappy path without guessing. Straight from the OpenAPI spec.

{
  "data": {
    "period": "2026-07-20",
    "total": 39588242618845.71,
    "held_by_public": 31817640840048.45,
    "intragovernmental": 7770601778797.26,
    "unit": "US dollars",
    "source": "US Treasury"
  },
  "meta": { "source": "U.S. Treasury Fiscal Data", "area": "us" }
}

{
  "error": { "code": "NO_DATA", "message": "No debt data available yet" }
}

{
  "error": {
    "code": "VALIDATION_ERROR",
    "message": "Invalid query parameters",
    "details": [{ "param": "limit", "message": "Too big: expected number to be <=100" }]
  }
}

{
  "data": [
    { "period": "2025-09-30", "value": 37637553494935.61,
      "unit": "US dollars", "source": "US Treasury" },
    { "period": "2024-09-30", "value": 35464673929171.69,
      "unit": "US dollars", "source": "US Treasury" }
  ],
  "meta": { "source": "U.S. Treasury Fiscal Data", "area": "us",
            "count": 2, "next_end": "2024-09-29" }
}

{
  "data": [
    { "class": "total", "period": "2026-06-30", "rate": 3.409,
      "unit": "percent", "source": "US Treasury" },
    { "class": "bills", "period": "2026-06-30", "rate": 3.706,
      "unit": "percent", "source": "US Treasury" }
  ],
  "meta": { "source": "U.S. Treasury Fiscal Data", "area": "us" }
}

{
  "error": {
    "code": "CLASS_NOT_FOUND",
    "message": "Unknown security class. Available classes: total, marketable, non-marketable, bills, notes, bonds, tips, frn"
  }
}

Errors, auth & limits

One uniform error contract everywhere: { "error": { "code", "message", "details?" } } with stable, machine-readable codes.

Sample — 401

{
  "error": {
    "code": "UNAUTHORIZED",
    "message": "Missing X-Api-Key header. Get a free key at https://synergicapis.com/signup.html"
  }
}

Sample — 429 QUOTA_EXCEEDED

{
  "error": {
    "code": "QUOTA_EXCEEDED",
    "message": "Monthly quota exhausted (500 requests on the free plan). Resets on the 1st (UTC) — or upgrade at https://synergicapis.com/#pricing"
  }
}

Every 200 (and monthly 429) carries RateLimit-Limit / RateLimit-Remaining / RateLimit-Reset describing your monthly quota; a per-minute 429 describes the minute window and adds Retry-After. Successful responses also ship ETag — send If-None-Match and a 304 costs you nothing new.

Bulk data (CSV)

Want the whole series as a file? Download it — free, attribution appreciated. For live, always-fresh data use the API.

License: underlying data is U.S. government public domain (Treasury); this CSV compilation is free to use with attribution to its official source. Regenerated on releases — the API is always the freshest.

Data provenance

Every number traces to a named official dataset — never scraped, never estimated.

Example

# Today's debt, to the penny
curl -H "X-Api-Key: sk_live_YOUR_KEY" \
  https://api.synergicapis.com/debt/latest

import requests

r = requests.get(
    "https://api.synergicapis.com/debt/latest",
    headers={"X-Api-Key": "sk_live_YOUR_KEY"},
)
r.raise_for_status()
d = r.json()["data"]
print(f"US debt on {d['period']}: ${d['total']:,.2f}")

const res = await fetch("https://api.synergicapis.com/debt/latest", {
  headers: { "X-Api-Key": "sk_live_YOUR_KEY" },
});
const { data } = await res.json();
console.log(`US debt on ${data.period}: $${data.total.toLocaleString()}`);

// claude_desktop_config.json / ~/.cursor/mcp.json
{
  "mcpServers": {
    "synergic-apis": {
      "command": "npx",
      "args": ["-y", "@synergic-apis/mcp"],
      "env": { "SYNERGIC_API_KEY": "YOUR_API_KEY" }
    }
  }
}

{
  "data": {
    "period": "2026-07-20",
    "total": 39588242618845.71,
    "held_by_public": 31817640840048.45,
    "intragovernmental": 7770601778797.26,
    "unit": "US dollars",
    "source": "US Treasury"
  },
  "meta": { "source": "U.S. Treasury Fiscal Data", "area": "us" }
}

Live demo

Real request against the production API — no key needed here (demo endpoint, 5 requests/minute).

Press the button to fetch today's national debt.

Get started

Related