ICS MIME Type

About iCalendar files

Used for “Add to calendar” links and calendar subscriptions. With the right type, phones and desktop mail apps offer to add the event; a calendar feed that should stay in sync is linked with webcal:// instead of https://. Lines must end in CRLF, and long lines are folded at 75 bytes.

File signature

ICS files start with "BEGIN:VCALENDAR". The extension and the type a browser reports for an upload both come from the file name, so check these bytes on the server before trusting a file.

Serve .ics with the right Content-Type

Content-Type: text/calendar; charset=utf-8

text/calendar ics ifb;

AddType text/calendar .ics .ifb
AddCharset UTF-8 .ics .ifb

@ics path *.ics *.ifb
header @ics Content-Type "text/calendar; charset=utf-8"

curl -sI https://example.com/file.ics | grep -i '^content-type'
# Content-Type: text/calendar; charset=utf-8

Set the type in code

res.set('Content-Type', 'text/calendar; charset=utf-8');

import mimetypes

mimetypes.add_type('text/calendar', '.ics')  # if your system doesn't know it
mimetypes.guess_type('file.ics')[0]  # 'text/calendar'

mime.AddExtensionType(".ics", "text/calendar; charset=utf-8")
w.Header().Set("Content-Type", "text/calendar; charset=utf-8")

Accept .ics uploads

<input type="file" accept=".ics,.ifb,text/calendar">

The accept attribute only filters the file picker; users can still choose another file. Listing the extension as well as the type matters, because operating systems don’t always report the type you expect.

Related types

• .txt (text/plain): Plain text
• .csv (text/csv): CSV
• .json (application/json): JSON

More data and text

.tsv , .md , .ndjson , .jsonld , .xml , .yaml , .geojson , .sql . Look up any extension or type with the MIME type lookup.

Sources

• IANA registration: text/calendar
• MDN: Common media types

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Frequently asked questions