How to Choose the Best Calendar API in 2026
There are 16 Calendar APIs in our directory. Of these, 10 require no authentication, making them ideal for quick prototyping. 10 are rated beginner-friendly.
Scores last tested: 2026-08-10
Quick Comparison: Top 10 Calendar APIs
Ranked by API Score. Measured means we called a real endpoint of that API; Est. means the score is derived from metadata because the endpoint could not be called without credentials. Discontinued APIs are excluded.
| Name | API Score | Auth | HTTPS | CORS | Difficulty |
|---|---|---|---|---|---|
| Public Holidays | 92 A+ Est. | API Key | ✓ | ✓ | Intermediate |
| Nager.Date | 88 A Measured | No Auth | ✓ | ✗ | Beginner |
| Non-Working Days | 87 A Est. | No Auth | ✓ | ? | Beginner |
| Non-Working Days | 87 A Est. | No Auth | ✓ | ✓ | Beginner |
| UK Bank Holidays | 87 A Est. | No Auth | ✓ | ? | Beginner |
| Russian Calendar | 84 A Est. | No Auth | ✓ | ✗ | Beginner |
| Festivo Public Holidays | 82 A Est. | API Key | ✓ | ✓ | Intermediate |
| Holidays | 82 A Est. | API Key | ✓ | ? | Intermediate |
| Checkiday - National Holiday API | 77 B Est. | API Key | ✓ | ? | Intermediate |
| LectServe | 77 B Est. | No Auth | ✗ | ? | Beginner |
Free Calendar APIs (No Auth)
These APIs require no API key or signup. Start using them immediately.
Church Calendar
⭐ Beginner's PickChurch Calendar (calapi.inadiutorium.cz) is a free, no-auth REST API that returns the Roman Catholic liturgical calendar for any date or month.
Czech Namedays Calendar
⭐ Beginner's PickThe Czech Namedays Calendar API lets you look up the Czech or Slovak nameday (svátek) associated with a given first name, or find whose nameday falls on a specific date.
Hebrew Calendar
⭐ Beginner's PickThe Hebcal API provides free Jewish calendar data including Hebrew date conversions, Shabbat candle-lighting times, Jewish holidays, and weekly Torah portion readings.
LectServe
⭐ Beginner's PickLectServe is a free REST API that returns Revised Common Lectionary readings — Scripture passages assigned to each Sunday and feast day used by many Protestant denominations.
Nager.Date
⭐ Beginner's PickNager.Date is a completely free, open-source REST API providing public holidays for over 90 countries with no API key required.
Namedays Calendar
⭐ Beginner's PickNamedays Calendar provides name day traditions for dozens of countries, letting you look up which names are celebrated on any given date.
Try It in 5 Minutes: Nager.Date
Quick implementation example using Nager.Date.
Using curl
curl 'https://date.nager.at/api/v3/PublicHolidays/2024/US'
JavaScript
const url = "https://date.nager.at/api/v3/PublicHolidays/2024/US";
const response = await fetch(url);
if (!response.ok) throw new Error(`Request failed: ${response.status}`);
const data = await response.json();
console.log(data); New to APIs? Read our Getting Started Guide →
Frequently Asked Questions
How many Calendar APIs are available?
There are 16 Calendar APIs in our directory as of 2026.
Are there free Calendar APIs?
Yes, 10 Calendar APIs require no authentication and are completely free to use.
What is the easiest Calendar API to use?
Nager.Date is one of the easiest to get started with. It is rated as beginner-level and requires no authentication.
Do I need an API key for Calendar APIs?
It depends. 10 APIs need no authentication, 5 require an API key, and 1 use OAuth.