It once worked well, it still does in Chrome no good any more in Firefox, I will remove it and cease to use Diigo anymore.

Well - it works, but beware that when you're on the Free plan, you have a limit of 500 annotations, and it's not mentioned on their webpage or during the sign-up process, which is shady.

Keep in mind that you can still make annotations after you hit your limit, but making a new one will force you to dismiss a popup box that tells you that you're over quota, and will nag you every time you visit their webpage.

The premium subscription is priced ridiculously, at 40$ a year. It certainly DOES NOT cost them 40$ a year to host small text files and a few megabytes of cached content. Developers should be paid for their work, but what they're charging is far too much for such a basic service. In contrast, you could get 100GB of Google Drive storage for 25$/year, and Apollo Ultra costs 10$/year, and that developer actually communicates, updates the app and is transparent about their billing practices.

Not only that, but updates are extremely rare (just take a look at their blog page, the last post is from May 2018), and their "Groups" social feature looks like it hasn't been updated since 2008. It's also filled with spam.

All I want is an extension that allows me to annotate without connecting to any cloud-based service (Seeing how they barely update anything, security is a concern).

Alternatives to Diigo are relatively hard to find. I would have thought that extensions that let you highlight, annotate and tag would have been more commonplace, but the only actual alternative I found was hypothes.is. That service is updated much more frequently, and costs nothing for non-LMS uses. The main drawback to that, however, is the rather clunky UI that doesn't play well with NoScript and the lack of an official Firefox extension, as well as the constant cloud connectivity.

wonderful little helper!

Can't make line breaks in notes. (When you press "enter" in a note, nothing happens).

A shame, because this extension works great in Chrome.

I use this ass-on to animate a school mag with students (10 to 15) and find it very usefull

It's useful for schoolwork. And for annotating articles.

i am a paying client since 4 or 5 years, the Firefox version of the highlighter works in 80% of the pages in chrome works perfect. Updates come every 2 years or something like that? ...painful. I continue paying because there is no decent alternative, it's a pity

Cannot sign in, cannot find support to get extension working. Stuck in an endless loop of asking me to sign in.

I like Diigo. Works well. Use it for annotating websites to find back relevant information.

This extension was always clunky but since few weeks, it does not work at all. I highlight pages, they appear highlighted and when I revisit them, they are gone.
Few dozens notes went to waste before I realized all my work is not being saved.
I had "Professional" user tier mostly for assets fetching but this too stopped working.
Diigo prides itself in staying online for 10 years now: being online is one, keeping your product working in ever-changing Web is another.

Excellent add-on and service.

This is the best thing after del.icious gone wrong. A very good bookmark organizer. I wish they had a backup feature where you could export all the bookmarks in html. I miss it a lot.