Diigo

Diigo is a cloud‑based research and collaboration platform that allows users to bookmark, annotate, and share web pages, PDFs, and other online resources. The service was launched in 2007 by Vijay Gupte as a groupware tool that combined traditional bookmarking with social networking features. Over time, Diigo expanded its functionality to include highlights, sticky notes, sticky tabs, and a private group feature for team collaboration.

The core of Diigo is the bookmarking engine, which assigns a unique identifier to each saved URL and supports tags for organizing content. Annotative tools enable users to highlight text, add comments, and attach sticky notes, making it popular among academic researchers, students, and knowledge workers. Users can create private lists or public tags that are searchable across the Diigo community, fostering knowledge sharing and discovery.

Diigo offers desktop, web, and mobile interfaces, allowing synchronization across devices. Advanced features include full‑text search of annotations, integration with reference management software, and the ability to export bibliographic data in formats such as BibTeX. The platform also supports group-based collaboration, facilitating shared research projects and corporate knowledge management.

The service is available under a freemium model. Basic account holders receive limited storage and bandwidth, while premium plans provide additional features such as increased storage, advanced search filters, and support for larger group collaborations. Diigo is widely used in academic, research, and business contexts to streamline information collection and collaborative exploration.