Diigo

Diigo is an online service for annotating, bookmarking, archiving, and sharing web pages. It is available as a web application, a browser extension, and an app for iOS and Android. The name Diigo is an abbreviation for the "Digest of Internet Information, Groups and Other stuff." The service allows users to annotate, highlight, and add notes to any web page, and these can be overlayed on the site and be made public or private. If public, other Diigo users can read, reply to, and interact in other ways with the notes.

Diigo is intended for synchronous or asynchronous collaboration and can help research groups collect and critique their resources. It is also used to help educators and students collect and organize online resources and websites.

Other features of the platform include the following:

• a personal library, so a user can collect all online knowledge in a single place
• highlighting, which can be used on any web page for personal reference or collaboration
• an outline feature, which allows a user to structure their research by automated streamlining through Diigo or through personal customization
• tagging, for users to bookmark sites with relevant terms for easy future retrieval
• archiving of web pages, which is available for premium users. Resources are stored with the user's annotations intact, regardless of whether the original source is still active.

Diigo offers four tiers of plans, each with different features. The first tier is a Free tier, with limited use that is supported through advertising. The second tier is called the Standard tier; it costs USD $40 per year and offers unlimited cloud bookmarks, unlimited web page and PDF highlights, unlimited image storage, unlimited cache pages, and other related features.

The third tier is called the Professional tier, which costs USD $59 per year; it includes the features of the Standard tier plus unlimited PDF storage and unlimited outliners. The fourth tier is called the Business tier, which charges USD $10 per month per user. This tier offers all the features of the previous tiers, as well as unlimited team library storage for webpages, PDFs, and images; collaborative web annotations; collaborative PDF annotations; and an administrative console dashboard.

When Diigo launched their initial bookmarking tool and platform, it was to mixed reviews, with the bookmark and annotation space often offered as alternatives to a browser's built-in bookmark tool. It was a crowded space, with many other similar available options, and the tool was not considered to differentiate itself enough from others to be successful. To help compete, Diigo offered instant importing from other bookmarking services, especially those that were closely related.

Despite the initial poor reception, Diigo attracted users, and in 2009 Diigo acquired Furl, a web page clipping and archiving service. Furl was acquired from search advertising network company LookSmart for equity. The acquisition was made to help Diigo develop their product.

In 2012, Diigo suffered a web attack, in which the company's domain name was hijacked and transferred to another site. In 2013, Diigo announced the company was redesigning the product to make it more modern looking. At this point, the product had outlasted the various other bookmark and annotation products that in 2006 made the company's launch unremarkable, with most of those competitors either defunct, living dead, or only in limited use.

Since 2014, Diigo has worked to develop the company's product beyond a bookmarking, annotation, and collaborative research tool, toward being a knowledge management system capable of competing with other knowledge management tools. This includes features from the product's history as a bookmarking and annotation tool that other knowledge management tools did not possess. Some of these tools, for example, included a version of the Diigo tool for Kindle devices, allowing users to highlight and annotate a book on Kindle.