Amazon S3 Change file download name

In early January 2011 S3 added request header overrides. This functionality allows you to 'dynamically' alter the Content-Disposition header for individual requests.

See the S3 documentation on getting objects for more details.

With C# using AWSSDK,

GetPreSignedUrlRequest request = new GetPreSignedUrlRequest
{
    BucketName = BucketName,
    Key = Key,
    Expires = DateTime.Now.AddMinutes(25) 
};

request.ResponseHeaderOverrides.ContentDisposition = $"attachment; filename={FileName}";

var url = s3Client.GetPreSignedURL(request);

While the accepted answer is correct I find it very abstract and hard to utilize.

Here is a piece of node.js code that solves the problem stated. I advise to execute it as the AWS Lambda to generate pre-signed Url.

var AWS = require('aws-sdk');
var s3 = new AWS.S3({
    signatureVersion: 'v4'
});
const s3Url = process.env.BUCKET;

module.exports.main = (event, context, callback) => {
var s3key = event.s3key
var originalFilename = event.originalFilename

var url = s3.getSignedUrl('getObject', {
        Bucket: s3Url,
        Key: s3key,
        Expires: 600,
        ResponseContentDisposition: 'attachment; filename ="' + originalFilename + '"'
    });

[... rest of Lambda stuff...]

}

Please, take note of ResponseContentDisposition attribute of params object passed into s3.getSignedUrl function.

More information under getObject function doc at http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#getObject-property

I guess your cross posted this questions to Amazon S3 forum, but for the sake of others I'd like to post the answer here:

If there is only ever one "user filename" for each S3 object, then you can set the Content-Disposition header on your s3 file to set the downloading filename:

Content-Disposition: attachment; filename="foo.bar"

For the sake of fairness I'd like to mention that it was not me to provide the right answer on Amazon forum and all credits should go to Colin Rhodes ;-)