`res.download()`

Transfers a file as an attachment, prompting the browser to download it.

Since Express 4 Spec ↗

Syntax

res.download(path[, filename][, options][, callback])

Parameters

Name	Type	Required	Description
`path`	`string`	Yes	The path of the file to send.
`filename`	`string`	No	The name shown to the user in the download dialog.
`callback`	`function`	No	`(err)` invoked after the transfer or on error.

Returns

void — Streams the file; reports completion via callback.

Examples

app.get('/invoice/:id', (req, res) => {
  res.download(`./invoices/${req.params.id}.pdf`, 'invoice.pdf');
});

Output

Content-Disposition: attachment; filename="invoice.pdf"

app.get('/file', (req, res) => {
  res.download('./missing.txt', (err) => {
    if (err && !res.headersSent) res.sendStatus(404);
  });
});

Output

(404 Not Found)

Notes

Wraps `res.sendFile` plus the attachment header. Never build the path from raw user input - validate or resolve against a fixed base directory to prevent path traversal. Handle the callback error to avoid an unhandled exception when the file is missing.