It worked very well and the feature that you can sync Bookmark folders is pretty nice. However, since the upgrade to the newest Nextcloud/Bookmark version it has an error:
Nextcloud log: Call to undefined function gmp_init()
Edit: Now it works again, thanks for the help :)

This add-on made a mess of my bookmarks. It did not respect my bookmark folders or order, and ignored the folder I told it to make on the server side.

Nice try, would have loved to use it, but it is useless as it is now.

Webdavs work, but nextcloud keeps saying "E019: HTTP status 500. Failed GET request. Check your server configuration and log." It is my own nextcloud install- with bookmarks 1.0.6

Probably the only addon that supports sync on selected folders (not all bookmarks).
One feature i miss is support to force pull/push sync, sometimes i don't want to merge.

Funktionierte bei ersten Tests recht gut. Danke! Leider werden keine Tags synchronisiert. Die benötigt man für die Andriod App, da diese nun wieder keine Ordner kann. Ich werde sicher in 1...2 Jahren nochmal vorbei schauen. Danke!

Nginx + webdav module + floccus = ❤

It work's great, but it will be better (why it's only 4 star) if this app use oauth or the second factor (like u2f or otp), for the connexion, because i don't like the application password

First: works as it should without any restriction, very very good extension both for Firefox and my Nextcloud. Fifth star not assigned in fact that there's no Firefox add-on for Android version and so it is not usable for me for I don't have other devices to sync than my Android ones.
A minor proposal: A list view of the bookmarks like in Firefox itself would increase usability. The graphics for each bookmark are a bit large and if you have hundreds like me or maybe a thousand of them you're forced to scroll a lot or to use the search bar extensively.

Appendix: The list view is a comfortable advantage, thanks a lot.

Works as advertised, great dev support.

When Xmarks disappeared I was stuck for a while. But then I installed a NextCloudPi server at home which was pretty easy and has a load of benefits beside, and found floccus. It was was not working when I first tried it, but Marcel has been chipping away at it beautifully and as of version 3 it's well and truly slick and a satisfactory Xmarks replacement!

Translated by DeepL. Sorry about the possible nonsense:

It works fine, but why can't it be used with Firefox Sync active? FF Sync is essential for many people who use tab synchronization, password synchronization, history, sessions, plug-ins... I don't want to give up all that just to be able to synchronize my bookmarks, especially when I can also synchronize them with FF Sync, I just prefer to have them in my private cloud.
Please correct that important flaw, because it's a shame we can't have the best of both worlds.

Greetings

"Do one thing and do it well"
This add-on does what it's advertised to do, very easy to setup and uncomplicated.

Habe leider ähnliche Probleme wie andere Nutzer hier, versuche die Lesezeichen mit meiner NextCloud zu synchronisieren und es kommt der Fehler "Invalid bookmark: {"guid":"unfiled______}"

Gibt es hier keinen Workaround oder liegt die Ursache wirklich beim Autor der bookmarks App für Nextcloud?

EDIT:
Danke ich habe den Tipp mal versucht und versucht nur "Lesezeichen-Menü" zu synchronisieren, dann kommt aber nach einer Weile der Fehler "Trying to create a URL that is already bookmarked. This shouldn't happen! Please tell the developer about this!"
Offenbar wurde hier ein Teil doch schon synchronisiert, finde in NextCloud aber nicht heraus, wo ich diesen löschen kann...

Installed Floccus and registered an account in OwnDrive to backup bookmarks. The addon never synced.

At the left of the "Options" and "Sync Now" buttons it says "X Error!" and immediately below the buttons an error description says "JSON.parse: unexpected character at line 1 column 1 of the JSON data".
No idea what to do, error is not self-explanatory and does not give any hints regarding which JSON is crippled, nor a dump of such file; checked the GitHub site but could not make heads nor tails of the code (not a JS dev, more of a C# and VB.Net one I am).

Checked account "https://my.owndrive.com/" with my username and password and it browses OK. Would like the author to try an OwnDrive account, as they say it supports NextCloud, and post his findings, or at least a basic tutorial on how to set up Floccus with a third-party server, not just with localhost. I am not really sure of the URL to use; tried several (taken from the site being browsed in Firefox) to no avail. I'm sure I'm the one doing something wrong, but there are no good working examples of Floccus setups in the Mozilla not Addon Home pages.

Using FF 59.0.2 (64-bit) on Ubuntu 16.04.

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EDIT 1: Cannot reply to your reply, so using this edit.
Thanks a lot for the response.
No, I did not enable or install a Bookmarks app, and my guess is that I would have to do that on OwnDrive.
OwnDrive has its own applet that one would drag to FF Bookmarks to upload, but I guess that is not the one you refer to. Also, no versions given.
Can you help me providing an adequate Bookmarks App link? If it has install instructions for third-party servers like OwnDrive, much better.

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EDIT 2: Cannot reply to your reply, so using this edit.
Also tried Wolkli, does not even have a Bookmarks secction, looks like they removed it.
None of OwnDrive or Wolkli allow adding apps to their free accounts. So the addon isn't any good to me. It could work for people that have their own NextCloud server, but not my case. Too bad.
In view of this, I'll give 4 stars to the addon.

Thanks for your great work so far.
Gave you some little support on liberapay - and this is what other people explaining here should do as well - this an open source application developed by one guy in his freetime. I value that.

Firefox Android Support
The main feature currently missing for me is the firefox android support. This hasn't been done yet because of missing support of the API in firefox android. If anyone like me wants to speed up this feature - he can donate here:
https://www.bountysource.com/issues/56793689-implement-bookmarks-on-android

Link to bug in Floccus on github:
https://github.com/marcelklehr/floccus/issues/3

Link to bug for firefox android (Bugzilla):
https://bugzilla.mozilla.org/show_bug.cgi?id=1330160

Nach anfänglichen Schwierigkeiten läuft die Erweiterung inzwischen Perfekt und ist unverzichbar für mich! Herzlichen Dank nochmal für den tollen Support und die unglaublich schnellen Versionsupdates :-)

Thanks for adding folder/tag support! Firefox Bookmark sync has been iffy and XMarks really spoiled me until it went down the tubes.