How to use the US Per Diem API in JavaScript

GSA lodging and M&IE per diem rates for US cities by ZIP, state and fiscal year. This guide calls it from JavaScript with code we've run against the live endpoint.

Online · 660 msEndpoint tested Nov 15, 2026

1. What you need

Any modern browser. Paste the code into the DevTools console or a module script tag.

No API key or sign-up. Endpoint: https://us-per-diem-api.narwhalapis.workers.dev

2. Make the request

JavaScript

const res = await fetch("https://us-per-diem-api.narwhalapis.workers.dev");
if (!res.ok) throw new Error(`HTTP ${res.status}`);
const data = await res.json();
console.log(data);

3. The response

Trimmed from the live response on Nov 15, 2026.

JSON

{
  "name": "US Per Diem API (GSA FY2026/FY2027)",
  "description": "Official GSA lodging and meals & incidentals (M&IE) per diem rates by ZIP, ci...",
  "endpoints": [
    "/v1/meta",
    "/v1/rates",
    "/v1/mie"
  ],
  "example": "/v1/rates?zip=10001",
  "links": {
    "docs": "https://narwhalthepong.github.io/gumroad-license-check/free-tax-finance-api",
    "rapidapi": "https://rapidapi.com/narwhalapis/api/us-per-diem-api-gsa-lodging-m-ie-rates-2026",
    "openapi": "/openapi.json",
    "spreadsheet": "https://payhip.com/b/ztfN3"
  },
  "free": "Free to use; please keep request rates reasonable.",
  "version": "1.0.0"
}

4. Before you ship

Set a timeout and handle non-200 responses: free APIs can rate-limit or go down.
Cache responses where you can, instead of calling the API on every page view.
Browser calls depend on CORS. If a request is blocked, move it to a server or serverless function.
Read the official documentation ↗ for rate limits and terms of use.

FAQ

Does the US Per Diem API need an API key in JavaScript?

No. The US Per Diem API works without an API key, so the JavaScript example runs as-is.

Can I call the US Per Diem API from the browser?

Yes. It sends CORS headers, so front-end JavaScript can call it directly.

What does the US Per Diem API return?

JSON. The example response on this page is trimmed from a real response our health check received on Nov 15, 2026.

Same API in: Python · Node.js · PHP · Java · Go · Ruby · C#
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