VoiceThread is a cloud-based application — no software installation required — which enables users to collaborate and share documents, add images, videos and sound in a shared space. It allows instructors to post a series of photos (or other media) and ask learners to respond and share answers. Users can use voice, text or video comments.

Instructors and learners can use VoiceThread to share documents, projects, presentations, videos and images. The audience can then comment on the VoiceThread slides using one of five options: microphone, webcam, text, phone and audio-file upload. Users also have the option of keeping VoiceThread private, sharing it with a group or making it available to other VoiceThread users worldwide.

Free access:
https://voicethread.com/