Content-Type for CSV File Downloads

CSV Content-Type

CSV (Comma-Separated Values) files use the text/csv media type. Proper charset declaration is critical for non-ASCII data.

The Header Value

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

Header Parameter

The header parameter indicates whether the first row contains column names:

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

Values: present or absent.

Triggering Download

To make the browser download the CSV rather than display it:

Content-Type: text/csv; charset=utf-8
Content-Disposition: attachment; filename="export-2025-01.csv"

Excel Compatibility

Microsoft Excel may not correctly detect UTF-8 encoding. To ensure compatibility, prepend a UTF-8 BOM (Byte Order Mark) to the CSV content:

const BOM = "\uFEFF";
const csvContent = BOM + "Name,Email\nJohn,john@example.com";

Alternative: Tab-Separated Values

For tab-separated files, use:

Content-Type: text/tab-separated-values; charset=utf-8

curl Example

# Download a CSV export
curl -H "Accept: text/csv" \
  -o report.csv \
  https://api.example.com/reports/monthly.csv

fetch() Response Handling

const response = await fetch("/api/export.csv");
const blob = await response.blob();
const url = URL.createObjectURL(blob);
const a = document.createElement("a");
a.href = url;
a.download = "export.csv";
a.click();