Ics Diff API

POST https://api.findutils.com/api/tools/ics-diff/execute

Compare two iCalendar (.ics) exports of the same calendar, before and after, and report which events were added, removed or changed. Entries are matched by UID plus RECURRENCE-ID (a modified occurrence is its own entry), never by position or title; entries without a UID are listed and never matched. A changed entry lists each field that differs with its before and after values; repeated fields such as ATTENDEE or CATEGORIES show only the values that differ, and an alarm (VALARM) counts as a field. Property order, line folding and parameter order are not differences. DTSTAMP, LAST-MODIFIED and SEQUENCE are ignored by default because calendar apps rewrite them on every export. Times are compared as written, never converted between zones. Also returns the added and the removed entries as calendars of their own. No calendar URL is fetched.

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Request body

application/json

before

string required

The earlier .ics export (A).
after

string required

The later .ics export (B).
ignore_metadata

boolean optional

Leave DTSTAMP, LAST-MODIFIED and SEQUENCE out of the comparison. Default true. Default true.
include_todos

boolean optional

Also compare VTODO and VJOURNAL entries. Default false: events only. Default false.

Example arguments

Verified

{
  "before": "BEGIN:VCALENDAR\nVERSION:2.0\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART:20261005T063000Z\nSUMMARY:Standup\nLOCATION:Room 4\nEND:VEVENT\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART;VALUE=DATE:20261009\nSUMMARY:Dentist\nEND:VEVENT\nEND:VCALENDAR\n",
  "after": "BEGIN:VCALENDAR\nVERSION:2.0\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART:20261005T070000Z\nSUMMARY:Standup\nLOCATION:Room 7\nEND:VEVENT\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART;VALUE=DATE:20261012\nSUMMARY:Offsite\nEND:VEVENT\nEND:VCALENDAR\n"
}

curl -X POST https://api.findutils.com/api/tools/ics-diff/execute \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "before": "BEGIN:VCALENDAR\nVERSION:2.0\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART:20261005T063000Z\nSUMMARY:Standup\nLOCATION:Room 4\nEND:VEVENT\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART;VALUE=DATE:20261009\nSUMMARY:Dentist\nEND:VEVENT\nEND:VCALENDAR\n",
    "after": "BEGIN:VCALENDAR\nVERSION:2.0\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART:20261005T070000Z\nSUMMARY:Standup\nLOCATION:Room 7\nEND:VEVENT\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART;VALUE=DATE:20261012\nSUMMARY:Offsite\nEND:VEVENT\nEND:VCALENDAR\n"
  }'

const response = await fetch('https://api.findutils.com/api/tools/ics-diff/execute', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json', Authorization: 'Bearer YOUR_API_KEY' },
  body: JSON.stringify({"before":"BEGIN:VCALENDAR\nVERSION:2.0\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART:20261005T063000Z\nSUMMARY:Standup\nLOCATION:Room 4\nEND:VEVENT\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART;VALUE=DATE:20261009\nSUMMARY:Dentist\nEND:VEVENT\nEND:VCALENDAR\n","after":"BEGIN:VCALENDAR\nVERSION:2.0\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART:20261005T070000Z\nSUMMARY:Standup\nLOCATION:Room 7\nEND:VEVENT\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART;VALUE=DATE:20261012\nSUMMARY:Offsite\nEND:VEVENT\nEND:VCALENDAR\n"}),
});
const data = await response.json();

import requests

response = requests.post(
    "https://api.findutils.com/api/tools/ics-diff/execute",
    headers={"Authorization": "Bearer YOUR_API_KEY"},
    json={"before":"BEGIN:VCALENDAR\nVERSION:2.0\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART:20261005T063000Z\nSUMMARY:Standup\nLOCATION:Room 4\nEND:VEVENT\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART;VALUE=DATE:20261009\nSUMMARY:Dentist\nEND:VEVENT\nEND:VCALENDAR\n","after":"BEGIN:VCALENDAR\nVERSION:2.0\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART:20261005T070000Z\nSUMMARY:Standup\nLOCATION:Room 7\nEND:VEVENT\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART;VALUE=DATE:20261012\nSUMMARY:Offsite\nEND:VEVENT\nEND:VCALENDAR\n"},
)
data = response.json()

$ch = curl_init('https://api.findutils.com/api/tools/ics-diff/execute');
curl_setopt_array($ch, [
    CURLOPT_POST => true,
    CURLOPT_HTTPHEADER => ['Content-Type: application/json', 'Authorization: Bearer YOUR_API_KEY'],
    CURLOPT_POSTFIELDS => '{"before":"BEGIN:VCALENDAR\nVERSION:2.0\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART:20261005T063000Z\nSUMMARY:Standup\nLOCATION:Room 4\nEND:VEVENT\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART;VALUE=DATE:20261009\nSUMMARY:Dentist\nEND:VEVENT\nEND:VCALENDAR\n","after":"BEGIN:VCALENDAR\nVERSION:2.0\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART:20261005T070000Z\nSUMMARY:Standup\nLOCATION:Room 7\nEND:VEVENT\nBEGIN:VEVENT\nUID:[email protected]\nDTSTART;VALUE=DATE:20261012\nSUMMARY:Offsite\nEND:VEVENT\nEND:VCALENDAR\n"}',
    CURLOPT_RETURNTRANSFER => true,
]);
$data = json_decode(curl_exec($ch), true);

Also an MCP tool

Call ics_diff from Claude, Cursor or any MCP client. Same arguments, same output.

https://mcp.findutils.com

MCP reference

Rate limit: 60 a minute, per IP
Auth: API key
REST id: ics-diff
MCP name: ics_diff
Category: Productivity
Machine-readable: openapi.json · markdown.md

Request body

Example arguments

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