saljam
Copying file timestamp
Please consider transferring the file timestamp from the source to the destination, just like the file name
maybe also preserve file permissions?
both would only apply to the command line tool, and not the web interface.
perhaps emulate the stdlib's gzip API. Receiving multiple files could be just gzip.Reader in multistream mode. In that lib, each file gets metadata in gzip.Header (https://golang.org/pkg/compress/gzip/#Header)
Note you can already do this with the pipe subcommand.
On one end:
tar cz . | ww pipe
4-framework-gossamer
...
On another:
ww pipe 4-framework-gossamer | tar xz
With compression too!
Considering this only makes sense on the command line (we can't change metadata on file downloaded by browser) my preference would be to push as much of this as possible onto other tools in general to avoid too much divergence, but I'll leave this one open since it fairly simple.