Downloading FASTQ Files Quickly utilizing IBM’s Aspera Connect on a LINUX or MAC Machine

Please note that this guide is based on this BioStars thread and this GitHub repository


  1. Download the latest version of Aspera Connect from the IBM “featured client software” section (you may need to install a browser extension as well)

  1. Download the file “” from wwood’s GitHub repository

  1. Open the script in your favorite python editor and scroll down to the bottom. Add the specific file path to the ascp field (addition highlighted below)

aspera_commands = []

    for url in ftp_urls:

        quiet_args = ''

        if args.quiet:

            quiet_args = ' -Q'

        cmd = "/Users/USER/Applications/Aspera\{} -T -l 300m -P33001 {} -i {}{} {}".format(




            url.replace('',''), output_directory)"Running command: {}".format(cmd))

        subprocess.check_call(cmd,shell=True)"All done.") 

  1. Save the file. Move the file to the directory where you want FASTQ files to be deposited into. Run the following command in terminal for each accession number (example highlighted):

./ ERR1739691 --ssh_key osx 

Note: Sequential commands can be done through a looped text file call or with the ; operator (ex. ./ key1 --ssh_key osx ; / key2 --ssh_key osx)

Note 2: For this method it is recommended that you utilize a bash terminal.