go get -u github.com/lukaselmer/link-to-download
cd $GOPATH/src/github.com/lukaselmer/link-to-download
bin/rungit push heroku master
heroku openhttp://link-to-download.dev:3000/store?api_key={{API_KEY}}&url=https://{{FILE_URL-ending-with-.pdf}}
Result:
{
"persistentLink":"https://s3-...",
"temporaryLink":"http://link-to-download.dev:3000/download/..."
}