On its own, Frostwire is a very safe program free of viruses and spyware. However, since Frostwire is a filesharing program, it is only as safe as the files it downloads.
Frostwire was once a fork of Limewire that made use of the Gnutella network to share files. However, as of version 5, it has dropped Gnutella support entirely. It is now a BitTorrent client, which means that it can download parts of a large file from multiple clients simultaneously and upload those parts to others. To diminish the probability of downloading viruses and malware, users should torrent files only from trusted websites and uploaders. Users can also look at the comments for a specific torrent to ensure that other users have downloaded it without issue. Finally, users should scan files downloaded through FrostWire using a trusted antivirus program.