M
API Matrix

Checkiday - National Holiday API API

Calendar / API Key Intermediate HTTPS
Varies by plan (check documentation)
77 Score
Grade B
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Overview

Checkiday is a holiday data API covering more than 5,000 national days and observances in the United States, including unofficial holidays like National Pizza Day. It lets you query by date to retrieve all holidays for that day, along with descriptions and links to detailed information. An API key from APILayer is required.

💡

Beginner Tip

The free tier on APILayer provides 100 requests/month — enough for testing. Pass your key in the apikey header, not as a query parameter, which is the most common setup mistake.

Available Data

country name and code
population
capital city
region and subregion
flag image URL
event dates and names

Example Response

JSON Response 
{
  "name": "Japan",
  "capital": "Tokyo",
  "population": 125800000,
  "region": "Asia",
  "languages": [
    "Japanese"
  ],
  "flag": "https://flagcdn.com/jp.svg",
  "currencies": [
    {
      "code": "JPY",
      "name": "Japanese yen"
    }
  ]
}

Field Reference

holidays[].id Unique slug identifier for the holiday, e.g., "independence-day".
holidays[].name Display name of the holiday, e.g., "Independence Day".
holidays[].url URL on Checkiday.com with detailed information and history about the holiday.
date The queried date echoed back in YYYY/MM/DD format.
timezone Timezone used to determine the current date; defaults to America/Chicago.

Implementation Example 

const url = "https://apilayer.com/marketplace/checkiday-api";
// Replace headers or query params with the values required by this API.
const response = await fetch(url, {
  headers: {
  "X-API-Key": "YOUR_API_KEY"
  }
});
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data);

What Can You Build?

Note: These code examples are AI-generated and unverified. Always refer to the official API documentation for accurate usage.

Common Errors & Troubleshooting

401 Unauthorized API key not passed in the apikey header
✓ Add the header -H "apikey: YOUR_KEY" to your request; this API uses a header, not a query parameter.
Empty holidays array Date string formatted incorrectly
✓ Use the format YYYY/MM/DD (e.g., 2024/07/04) with forward slashes, not dashes or other separators.
429 Rate limit exceeded Exceeded the monthly quota on the free plan
✓ Cache responses for each date you query; holiday data for a given date does not change year-over-year.

Matrix Score Breakdown

🌐 Reachability 30/30
⚡ Speed 10/20
🔒 Security 15/15
🛠 Developer XP 12/20
✓ Reliability 10/15

Partially tested on Apr 5, 2026

Technical Specifications

Auth API Key
HTTPS REQUIRED
CORS UNKNOWN
Category Calendar
Difficulty Intermediate
Verified: 2026-04-07

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