What MIME type should I use for CSV?

I've seen application/csv used and also text/csv.

Is there a difference? Does it matter which as long as the request matches something that's available? Are they interchangeable?

RFC 7111

There is an RFC which covers it and says to use text/csv.

This RFC updates RFC 4180.

Excel

Recently I discovered an explicit mimetype for Excel application/vnd.ms-excel. It was registered with IANA in '96. Note the concerns raised about being at the mercy of the sender and having your machine violated.

>

Media Type: application/vnd.ms-excel

> > Name Microsoft Excel (tm) > > Required parameters: None > > Optional parameters: name > > Encoding considerations: base64 preferred > > Security considerations: As with most application types this data is > intended for interpretation by a program that understands the data on > the recipient's system. Recipients need to understand that they are at > the "mercy" of the sender, when receiving this type of data, since > data will be executed on their system, and the security of their > machines can be violated. > > OID { org-id ms-files(4) ms-excel (3) } > > Object type spreadsheet > > Comments This Media Type/OID is used to identify Microsoft > Excel generically (i.e., independent of version, subtype, or platform format).

I wasn't aware that vendor extensions were allowed. Check out this answer to find out more - thanks starbeamrainbowlabs for the reference.

You should use "text/csv" according to RFC 4180.

Strange behavior with MS Excel: If i export to "text based, comma-separated format (csv)" this is the mime-type I get after uploading on my webserver:

[name] => data.csv
[type] => application/vnd.ms-excel

So Microsoft seems to be doing own things again, regardless of existing standards: https://en.wikipedia.org/wiki/Comma-separated_values

My users are allowed to upload CSV files and text/csv and application/csv did not appear by now. These are the ones identified through finfo():

text/plain
text/x-csv

And these are the ones transmitted through the browser:

text/plain
application/vnd.ms-excel
text/x-csv

The following types did not appear, but could:

application/csv
application/x-csv
text/csv
text/comma-separated-values
text/x-comma-separated-values
text/tab-separated-values

For anyone struggling with Google API mimeType for *.csv files, I have found the list of MIME types for google api docs files

Google Doc Format	Conversion Format	Corresponding MIME type
Documents	HTML	text/html
	HTML (zipped)	application/zip
	Plain text	text/plain
	Rich text	application/rtf
	Open Office doc	application/vnd.oasis.opendocument.text
	PDF	application/pdf
	MS Word document	application/vnd.openxmlformats-officedocument.wordprocessingml.document
	EPUB	application/epub+zip
Spreadsheets	MS Excel	application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
	Open Office sheet	application/x-vnd.oasis.opendocument.spreadsheet
	PDF	application/pdf
	CSV (first sheet only)	text/csv
	TSV (first sheet only)	text/tab-separated-values
	HTML (zipped)	application/zip
Drawings	JPEG	image/jpeg
	PNG	image/png
	SVG	image/svg+xml
	PDF	application/pdf
Presentations	MS PowerPoint	application/vnd.openxmlformats-officedocument.presentationml.presentation
	Open Office presentation	application/vnd.oasis.opendocument.presentation
	PDF	application/pdf
	Plain text	text/plain
Apps Scripts	JSON	application/vnd.google-apps.script+json

Source here: https://developers.google.com/drive/v3/web/manage-downloads#downloading_google_documents the table under: "Google Doc formats and supported export MIME types map to each other as follows"

There is also another list

MIME Type	Description
application/vnd.google-apps.audio
application/vnd.google-apps.document	Google Docs
application/vnd.google-apps.drawing	Google Drawing
application/vnd.google-apps.file	Google Drive file
application/vnd.google-apps.folder	Google Drive folder
application/vnd.google-apps.form	Google Forms
application/vnd.google-apps.fusiontable	Google Fusion Tables
application/vnd.google-apps.map	Google My Maps
application/vnd.google-apps.photo
application/vnd.google-apps.presentation	Google Slides
application/vnd.google-apps.script	Google Apps Scripts
application/vnd.google-apps.site	Google Sites
application/vnd.google-apps.spreadsheet	Google Sheets
application/vnd.google-apps.unknown
application/vnd.google-apps.video
application/vnd.google-apps.drive-sdk	3rd party shortcut

Source here: https://developers.google.com/drive/v3/web/mime-types

But the first one was more helpful for my use case.