Windows/Mac/Linux: Free, open-source application Synkron is a powerful file-syncing utility that syncs files across platforms. The apps's marquee features include support for syncing multiple folders, automatic scheduled syncs, and restore capabilities for files that may have been accidentally overwritten during a sync. Apps like previously mentioned Dropbox boasting instantaneous sync between your PCs and the web are all the rage right now, but Synkron has its own appeal—namely that it's a local sync tool, so your files never pass through any third-party server. It also supports filtering by extension and file and folder blacklists. So while Synkron may not be up to the instant syncing standards you can expect from the likes of Dropbox, it does support complex backup schemes and is a great alternative. Synkron is free, works on all platforms.