Cusdis - Open-source, lightweight comment system for your website
Voicl - With Voicl you can easily embed voice notes onto your website.
Huddle - Huddle | The Enterprise Content Collaboration Platform
Telbee.io - telbee adds voice messaging to podcasts, websites, social media and email to easily hear from and build human relationships with your customers and community - save time, reduce frustration, and gain sales, understanding and fans
Coment - Online comments aggregated in one dashboard
Heyoya - Voice comments for websites & blogs