CSV MIME Type

About CSV files

Registered in RFC 4180, which also describes the format. For exports, send text/csv; charset=utf-8 with Content-Disposition: attachment; filename="export.csv". Excel ignores the charset header and guesses the encoding itself, so add a UTF-8 byte order mark (EF BB BF) at the start of the file if non-English text must open correctly in Excel.

• In upload forms, accept .csv by extension too: Windows browsers often report CSV files as application/vnd.ms-excel, and some as application/octet-stream.

Other types seen for these files: application/vnd.ms-excel , application/csv , text/x-csv . Accept them when reading uploads, but send text/csv yourself.

File signature

CSV has no fixed signature: it is text without a magic number, so validate uploads by parsing the content rather than by checking bytes.

Serve .csv with the right Content-Type

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

text/csv csv;

AddType text/csv .csv
AddCharset UTF-8 .csv

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

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

Set the type in code

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

import mimetypes

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

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

Accept .csv uploads

<input type="file" accept=".csv,text/csv">

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

• .tsv (text/tab-separated-values): TSV
• .xlsx (application/vnd.openxmlformats-officedocument.spreadsheetml.sheet): Excel workbook
• .json (application/json): JSON

More data and text

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

Sources

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

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Frequently asked questions