Open ICS File

Information, tips and instructions

Open ICS File

ICS file extension is used by iCalendar internet standard to store events, to-dos, free/busy information and journal entries. The ICS file format is defined in RFC5545 (

iCalendar standard is used by many online internet applications including:

  • Yahoo! Calendar
  • Google Calendar
  • Apple Calendar
  • Mozilla Thunderbird

iCalendar is a protocol independent standard. It means that events could be shared by different transports like e-mail, HTTP protocol and others.

To open ICS file you can either use a calendar application of your choice or if you don’t have one you can open ICS file in text editor and view information inside. Since iCalendar standard stores information as plain text it is possible to interpret information inside ICS file without special software.

To display iCalendar events in HTML pages hCalendar microformat was developed. Using hCalendar microformat on a web page allows any software which parses the page to correctly read and interpret iCalendar information. There are two different microformats for displaying iCalendar information. One is hCalendar which is based on “span” and “abbr” HTML tags. The other one is microformats2 update which uses “time” HTML tag. Microformats2 version is considered more suitable because of accessibility problems with original hCalendar version.

Besides ICS file extension iCalendar also uses IFB file extension to store information about free/busy time.

iCalendar is based on vCalendar created by the Internet Mail Consortium (IMC). vCalendar used VCS file extension for calendar data transfer.

Below is an example of iCalendar data file: BEGIN:VCALENDAR
PRODID:-//hacksw/handcal//NONSGML v1.0//EN
UID:[email protected]
ORGANIZER;CN=Test User:MAILTO:[email protected]
SUMMARY:Test Event

ICS files are transferred over e-mail or internet using text/calendar multipurpose internet mail extensions (MIME) type.

Get more information about how to open ICS file.

Also check how to open NOMEDIA file and open ASPX file on Open File Database.

If you are not able to open file with certain file extension make sure to check if extension for the file is correct. It is possible that information in the file doesn't match file extension.

File Extension Info

File Extension Info
AI File Opens With
Yahoo! Calendar
Google Calendar
Apple Calendar
Mozilla Thunderbird