Top Alternatives to Google Duo

Skype is an instant messaging and VOIP (Voice Over Internet Protocol) client to communicate with people in a distant place.

Hangouts is an instant messaging software developed by Google.

WhatsApp Messenger is an instant messaging platform owned by Facebook.

Tox is a peer-to-peer instant-messaging and video-calling protocol that offers end-to-end encryption.

Signal is the most scalable encryption tool.

Imo free video calls and chat is a kind of Communication apps for Android.

Empathy is an instant messaging (IM) and voice over IP (VoIP) client which supports text, voice, video, file transfers, and inter-application communication over various IM protocols.

Linphone is a free voice over IP (VoIP) service and SIP client.

Wire is a cross-platform, encrypted instant messaging client created by Wire Swiss. It is available for iOS, Android, Linux, Windows, macOS and Web browser clients.

FaceTime is a proprietary videotelephony product developed by Apple Inc. FaceTime Audio is an audio-only version.

appear.in provides one-click video conferences right in your browser without requiring PIN codes or additional software.

Tango is the messaging app with the best video calling. All messages and calls are free.

GoToMeeting provides easy online meetings with HD video conferencing.

Jitsi Meet is an open-source (Apache) WebRTC JavaScript application that uses Jitsi Videobridge to provide high quality, scalable video conferences.

Cisco WebEx provides on-demand collaboration, online meeting, web conferencing and video conferencing applications.