Unfortunately, not maintained anymore. As per reviews below, not synchronized anymore. Its source code GitHub.com/mozilla/notes is now archived-only - the project is closed.

It probably used to synchronize/upload the notes to "Mozilla Private Network" (NOT the same as Mozilla, or any, Virtual Private Network). But that is gone, too.

Could have been easy 5 stars if the notes would be synced (and backed up) via the Mozilla account. Otherwise, like S K Biswas said - do not use, your notes can disappear without warning.

Doesn't work. Why is this not updated? Did Mitchell Baker fire the employees working on this addon and than hoard all the funds so she can live a lavish lifestyle like other CEOs. Being rich and having FOMO will drag Mozilla down.

Would've been a decent notes addon except it constantly deletes saved notes.
For a time it works fine then suddenly one day all your notes are just gone. Unacceptable...

This Add-On corrupted my Bookmarks. I highly recommend 'NOT' to use it. You should also note that it was last updated 2 years ago (Sep 17, 2020).

It doesn't have sync.

please change the app icon. it looks terrible on toolbar.

on screenshot it shows sync! but, there's no sync actually. notes are not syncing!!!

"lets you take notes on web pages."

No it does not... The notes are not related to the webpages at all... It's just a notes sidebar.

Can't input chinese characters.

Deleted all my notes without reason.

Please optimize this extension for Firefox Android

this one day out of blue delete all my notes even not i had cleared my history or made anything unusual. Besides delete thoroughly my info it's impossible open on android

Obviously, synchronization is not perfect. If you delete the extension and install it, it'll be reset. Anyway.

No tiene diccionario español y las notas están subrayadas como mal escritas

J ai changé de téléphone, un transfert de toutes les données a été effectué .quand j ai ouvert notes sur le nouveau téléphone c etait vide j ai perdu toutes mes infos et je ne sais pas du tout comment les récupérer

Loved this app for it's simplicity. Then I had to reinstall my Firefox and all my content was gone. I lost a TON of important stuff. Thoroughly disappointed.

This is great feature in browser. No need to juggle between browser and other tools to make notes.
Edge has something in form of collection. which is better but I liked simplicity of notes in Firefox. But one day I rebooted my PC and all my notes disappeared. I have no clue why that happened. I'm using 78esr so there was no major upgrade happened to my browser.

I see other people having similar complains but seems developers have no clue or are not interested in helping. I lost some important information in those notes. :(

I've resetted my PC today and it seems that I lost all of my notes. Thanks Mozilla.

Fatal por discontinuarlo. Flaco favor a los principios de Mozilla

A great idea, but poorly executed. Lots of bugs and performance issues. This morning it won't open at all.

I lost all my notes and I don't know why :/
In which folder all the notes are being stored?

Looping between verify your account and reconnect...

I thought notes were associated or linked to the web page where they were taken, as it should. What's the goal of a notebook app in a browser if the notes are not related to the pages?