Best Calendar APIs in 2026

The top 15 of 22 free Calendar APIs, ranked by how easy they are to start with (API key, HTTPS, CORS), how reliable they are in our daily health checks, and what developers rate them. caldays API takes the top spot.

Last tested Oct 24, 2026 · Rankings update daily

1
caldays API
Online · 867 ms
Public holidays for 195+ countries.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
2
CountdownsHQ API
Online · 623 ms
Dates and timezone-correct countdowns for 150+ holidays and observances in 18 countries.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
3
The Calendar API
Online · 643 ms
Public holidays for US states and 30 countries plus sports and finance calendars as static JSON.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
4
UK Bank Holidays API
Online · 62 ms
Bank holidays in England and Wales, Scotland and Northern Ireland.
- No API key needed
- Fast: 62 ms response
- Returns JSON at its URL
- HTTPS
No authHTTPSCORS ?
5
India Public Holidays API
Online · 459 ms
Official Indian public holidays for the Central government and 36 states/UTs.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
6
Intellibook API
Online · 1280 ms
Appointment booking and availability API for salons and clinics.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
7N
Namedays Calendar API
Online · 616 ms
Provides namedays for multiple countries.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
8
Non-Working Days API
Online · 2770 ms
Simple REST API for checking working, non-working or short days for Russia, CIS, USA and other.
- No API key needed
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
9
Non-Working Days API
Online · 565 ms
Database of ICS files for non working days.
- No API key needed
- HTTPS
No authHTTPSCORS ?
10
Nager.Date API
Online · 1111 ms
Public holidays for more than 90 countries.
- No API key needed
- HTTPS
No authHTTPSNo CORS
11
Russian Calendar API
Online · 661 ms
Check if a date is a Russian holiday or not.
- No API key needed
- HTTPS
No authHTTPSNo CORS
12
Checkiday - National Holiday API
Online · 1152 ms
Industry-leading holiday data with over 5,000 holidays and thousands of descriptions.
- HTTPS
apiKeyHTTPSCORS ?
13
Holidays API
Online · 610 ms
Don't let sourcing and maintaining holiday information get in the way of building your product.
- HTTPS
apiKeyHTTPSCORS ?
14
Public Holidays API
Online · 1932 ms
Data on national, regional, and religious holidays via API.
- Callable from the browser (CORS)
- HTTPS
apiKeyHTTPSCORS
15C
Calendarific API
Online · 410 ms
Explore comprehensive holiday data worldwide with Calendarific.
- HTTPS
apiKeyHTTPSCORS ?

Calendar APIs compared

Top Calendar APIs compared
API	API key	HTTPS	CORS	Uptime	Response	Rating
caldays	No	Yes	Yes	Up	867 ms	Not rated
CountdownsHQ	No	Yes	Yes	Up	623 ms	Not rated
The Calendar	No	Yes	Yes	Up	643 ms	Not rated
UK Bank Holidays	No	Yes	Unknown	Up	62 ms	Not rated
India Public Holidays	No	Yes	Yes	Up	459 ms	Not rated
Intellibook	No	Yes	Yes	Up	1280 ms	Not rated
Namedays Calendar	No	Yes	Yes	Up	616 ms	Not rated
Non-Working Days	No	Yes	Yes	Up	2770 ms	Not rated
Non-Working Days	No	Yes	Unknown	Up	565 ms	Not rated
Nager.Date	No	Yes	No	Up	1111 ms	Not rated

More Calendar APIs

Best Calendar API FAQ

What is the best free Calendar API in 2026?

Based on access, reliability and developer ratings, the top free Calendar APIs right now are caldays API, CountdownsHQ API and The Calendar API. caldays API ranks first. Rankings update daily from health checks of all 22 Calendar APIs in the directory.

What is the best Calendar API without an API key?

caldays API, CountdownsHQ API and The Calendar API need no API key, so you can call them without signing up. 15 of the 22 ranked Calendar APIs are keyless.

Which Calendar API works from the browser?

caldays API, CountdownsHQ API and The Calendar API support CORS over HTTPS, so front-end JavaScript can call them directly without a proxy.

How are these APIs ranked?

Each API gets a score from: no API key (+), HTTPS (+), CORS support (+), 30-day uptime and response time from our daily health checks, and ratings from developers on this site. APIs that failed three checks in a row are left out until they recover.