Firefox Extensions to Social Bookmarking

SemanticScuttle is an open-source, self-hosted social bookmarking system that emphasizes structured tagging and collaborative knowledge management. It allows users to save, organize, and share bookmarks with a strong focus on semantic relationships between tags.

Kifi was a collaborative bookmarking tool designed to help teams organize, share, and discover web pages. By creating a full-text index of shared content and integrating with popular communication platforms like Slack and Google, Kifi made finding relevant links easier and fostered team knowledge sharing.

Pearltrees is a visual and collaborative web clipping and organization tool that allows users to collect, organize, and share virtually anything found online. It's designed to help users curate digital content in a visually intuitive way, facilitating knowledge management and collaboration.

StumbleUpon was a popular discovery engine that personalized web content recommendations based on user interests and activity. It helped users discover new websites, videos, images, and information.

Papaly is a robust online bookmark manager and startpage, designed to help users organize, discover, and share web links visually. It offers collaborative boards, real-time synchronization, and integration with various productivity tools to enhance workflow and information management.