Government Directory · Data API

United States Government Domain Names

The official list of every dot-gov domain and the agency that owns it.

The authoritative register of all registered .gov domain names, published by the US Cybersecurity and Infrastructure Security Agency. Each row gives the domain, whether it belongs to a federal, state, city, county or tribal body, and the owning agency and organisation. It is the ground truth for deciding whether a US government web address is genuine.

Get API key View docs

Source: CISA .gov Data - Full list of registered .gov domains · Public Domain (U.S. Government Work, CC0 1.0) · Source: Cybersecurity and Infrastructure Security Agency (CISA), .gov Program - dotgov-data.

Endpoints

Every request is authenticated with your X-API-Key and counted against your plan.

GET /v1/data/united-states-government-domain-names
GET /v1/data/united-states-government-domain-names/search?q=...
GET /v1/data/united-states-government-domain-names/{key}

Base path /v1/data/united-states-government-domain-names · full reference in the interactive docs. Also exposed as an MCP tool for AI agents.

Fields

Field	Type	Description
domain_name	str	The registered .gov domain name.
domain_type	str	Level of government, e.g. Federal Agency, State, City, County or Tribal.
agency	str	Parent agency or department responsible for the domain.
organization	str	Specific organisation or office that registered the domain.
city	str	City recorded for the registering organisation.
state	str	State or territory recorded for the registering organisation.

What you get

Every registered .gov domain in one flat table

Level-of-government classification (federal, state, city, county, tribal)

Owning agency and organisation for each domain

Exact-match lookup by domain for fast verification

Filter by agency, state or government level to build target lists

No personal contact details included

FAQ

Does this include .mil or .us domains?: No. It covers the .gov top-level domain only, which is restricted to US government organisations.
Are security contact emails included?: No. We deliberately drop the contact email column so the API carries no personal or role-inbox data.
How often does it change?: CISA republishes the register regularly as domains are added and retired; we re-ingest on that cadence.
Can I use it commercially?: Yes, it is a public domain US Government work released under CC0.

Pricing

Simple, transparent pricing

Start free, upgrade when you need more. All plans include full API access.

Free

$0forever

Get started and explore the API

100 requests/day

100 API requests per day
All endpoints included
Community support

Get Started

Pro

$9/month

For production apps and AI agents

10,000 requests/day

10,000 API requests per day
All endpoints included
Priority support
Usage dashboard

Upgrade to Pro

Enterprise

$49/month

Unlimited access for high-volume use

Unlimited requests

Unlimited API requests
All endpoints included
Priority support
Usage dashboard
Dedicated support channel

Go Enterprise

Getting Started

Start building in minutes

Register

Create an account to get your API key. It's free — no credit card required.

curl -X POST https://api.aristocles.com.au/v1/auth/register \
  -H "Content-Type: application/json" \
  -d '{"email": "you@example.com", "name": "Your Name"}'

Make a request

Use your API key in the X-API-Key header to authenticate requests.

curl https://api.aristocles.com.au/v1/data/asx \
  -H "X-API-Key: your_api_key_here"

Upgrade

Need more requests? Upgrade to Pro or Enterprise — you'll be redirected to Stripe Checkout.

curl -X POST "https://api.aristocles.com.au/v1/billing/checkout?tier=pro" \
  -H "X-API-Key: your_api_key_here"

Check usage

Monitor your daily request count and remaining quota at any time.

curl https://api.aristocles.com.au/v1/usage \
  -H "X-API-Key: your_api_key_here"