All patent-free formats works in proprietary system with free software.
Firefox (Opus, Theora, Vorbis, VP8)
Thunderbird (IMAP, SMTP, XMPP)
Evince (PDF, Djvu)
LibreOffice (ODT, ODS, ODP...)
VLC (Opus, FLAC, VP8, Theora, Vorbis)
SMplayer (Theora, Vorbis, VP8...)
GIMP (XCF, SVG, JPG, PNG, TIF, EPS...)
Inkscape (SVG, EPS, PDF)
Jitsi (XMPP and SIP with audio and video and video conference)
Deluge or qbittorrent-Windows / Transmission-OSX (.torrent files and magnet
links)
InfraRecorder-Windows / Burn-OSX (disc burn)
Now we have the VP9 codec, only in Chromium for now.
