Create .ics Calendar File Online

Create .ics calendar files for Google, Apple and Outlook: events, all-day events, recurrence, reminders, and yearly events on a lunar date (giỗ, rằm) expanded to solar dates.

Result

Press “Run” to see the result.

The ICS API builds iCalendar files (RFC 5545) that every calendar app imports: Google Calendar, Apple Calendar, Outlook, Thunderbird. Send one event as parameters or many as a JSON events array, each with a title, start (YYYY-MM-DDTHH:MM in Vietnam time, or a date for all-day events), end or duration_minutes, location, description, URL, recurrence rule (rrule, e.g. FREQ=WEEKLY;COUNT=10) and reminders (alarm_minutes). Text is escaped and long lines folded as the standard requires, and a VTIMEZONE for Asia/Ho_Chi_Minh is included.

Standard calendars cannot repeat an event on a lunar date. With lunar: { day: 10, month: 3, years: 10 } the API computes the solar date of that lunar date for each year (10/3 âm lịch → 26/4/2026, 16/4/2027…) and writes one event per year: death anniversaries (giỗ), rằm and mùng 1, lunar birthdays, Hung Kings Day. A day 30 in a 29-day month falls on the last day of the month.

The response is a downloadable .ics file; format=json returns the file content and the list of computed dates instead.

Use this in your code

curl -X POST "https://apibox.io.vn/v1/ics" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"name":"Lịch gia đình","format":"json","events":[{"title":"Giỗ ông nội","lunar":{"day":10,"month":3,"years":3,"from_year":2026},"all_day":true,"alarm_minutes":1440}]}'

const res = await fetch('https://apibox.io.vn/v1/ics', {
  method: 'POST',
  headers: {
    Authorization: 'Bearer YOUR_API_KEY',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    "name": "Lịch gia đình",
    "format": "json",
    "events": [
      {
        "title": "Giỗ ông nội",
        "lunar": {
          "day": 10,
          "month": 3,
          "years": 3,
          "from_year": 2026
        },
        "all_day": true,
        "alarm_minutes": 1440
      }
    ]
  }),
});
const data = await res.json();
console.log(data);

import requests

res = requests.post(
    "https://apibox.io.vn/v1/ics",
    headers={"Authorization": "Bearer YOUR_API_KEY"},
    json={"name": "Lịch gia đình", "format": "json", "events": [{"title": "Giỗ ông nội", "lunar": {"day": 10, "month": 3, "years": 3, "from_year": 2026}, "all_day": True, "alarm_minutes": 1440}]},
    timeout=30,
)
print(res.json())

<?php
$ch = curl_init('https://apibox.io.vn/v1/ics');
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_CUSTOMREQUEST => 'POST',
    CURLOPT_HTTPHEADER => ['Authorization: Bearer YOUR_API_KEY', 'Content-Type: application/json'],
    CURLOPT_POSTFIELDS => '{"name":"Lịch gia đình","format":"json","events":[{"title":"Giỗ ông nội","lunar":{"day":10,"month":3,"years":3,"from_year":2026},"all_day":true,"alarm_minutes":1440}]}',
]);
$response = curl_exec($ch);
print_r(json_decode($response, true));

API documentation → Get a free API key

FAQ

How do I repeat an event every lunar year?

Use lunar: { day, month, years, from_year }. Calendar apps have no lunar recurrence, so the API writes one event per year with the right solar date.

Which time zone is used?

Times are Vietnam time (Asia/Ho_Chi_Minh, UTC+7); the file includes the time zone definition so apps abroad show the right local time.

Can I add reminders?

Yes, alarm_minutes (a number or an array of up to 5) adds display alarms before the event.