What do you mean by no option to save sessions?
There's a red heart icon that has a tooltip with "Save Session".
Auto-save is not saving in bookmarks, only manual saving will do so because otherwise I would create thousands of almost useless bookmarks for users.
The addon should work as intended, but in case some other addon creates some weird incompatibility it might not, but that's something I can't fix or change. Though, there should clearly be no issues to save a certain session.

Hi. It's a little hard for me to understand why the complain having in mind that the addon is specifically built for manual saving of sessions AS BOOKMARKS. There's no way that would be automatically because the addon would make firefox unresponsive every 10 seconds otherwise. Saving tens of bookmarks or even hundred is not acceptable for performance reasons. Yes, the addon has another small feature that saves in background everything once ever 15 seconds (or whatever you set), but that's clearly not something full featured and can't be compared with an auto-save session addon. I totally understand that the addon may not be for everyone, but I'm not even trying to promote it to those that want auto-saving :|. The description says that "you can save sessions as bookmarks" not that they are automatically saved.
This addon is intended for those that want control over what and when they want things to be saved and on top of that is made for management using the bookmark system. Don't want to be mean, but I'm not trying to sell the addon as what it's not, so giving it a 1 star for something that is not even suppose to be doing is not really ok.

Sorry for the issue you had. Sadly when Firefox crashes sadly many strange errors can happen to the Firefox profile as well and sometimes (very rarly) even to profile storage data (like bookmarks). Of course that I can't fix since it has nothing to do with the addon itself. As regarding the Multi-account container, simply I have my hands quite tied because there is no reliable way of storing anything beside a bookmarks. Whatever storage I might use, be it local or cloud based on profile a lot of strange issues can happen. For example local storage is deleted right away if you disable an addon. That's means you can only rely on it if it makes sense. But having half of the data stored in bookmarks and half in another place is very problematic when the other place is wiped out suddenly :|. Sorry for the missing feature, I might be able to find a solution at some point but I can't tell when it will be implemented.

Thanks for review and for using the addon. Yes, sadly there are a quite few missing features but in time I hope to close the gap and be able to provide as many options as possible to meet everyone's expectation.

I will try to give another chance to the API. It was suppose to work "out of the box" or that's just what Mozilla says but when I put it on mobile everything was blank. No errors, no issue no nothing, just a blank screen, and I had to cancel mobile support because simply I had no idea what the issue was and/or what to do. But I will try to check again if things work better. Sadly if there is any need to redo the UI for mobile things might not be that straight-forward so I can't really promise anything.

P.S Just in case you were not aware: All your saved sessions (in bookmarks) are still accesiable on Firefox mobile if you look for them in Bookmarks->Menu->SessionSync. I know it's not ideal but at least there something and you can still look up for things if you really need to.

Updated after user answer:

Thanks a lot for the detailed explanation of the issue. I promise that I will go through each one and investigate it thoroughly to find the bug.

Regarding the other 2 issues:
1. The scrollbar is awfully small on purpose, let's just say by design (I thought that a non intrusive scroll bar is better because I expected most people to just use the mouse scroll )... of course, it doesn't have to be like that, it can be stupid small and I totally understand that. I will make sure to add an option to configure it to be just normal. Regarding the interference from the popup with the scrollbar... this one also on purpose because it looked a little out of place to move it near the scrollbar. Not really sure who to approach some things having in mind that there's no real solution to place everything on screen and not affect something else. I will think about it. The fact that the mouse can be glitchy sometimes... I'm afraid that can't be something from be but most probably from the addon popup window (if in the Tab View it doesn't happen then that's for sure)

2. Need to investigate that further, because it seems really weird

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Are you sure they are not just in reverse order ? Depending on certain Firefox setting each user has, tabs can be restored in reverse order or in the normal order (If for example you activated new tabs to be opened next to the current one or similar settings). This is not something I can control myself since each user can affect the order of the tabs. I just simply tell firefox to open all the links no matter how many they are. If there are 1000 tabs I tell Firefox to open all of them in the right order they were saved. I wish there was something wrong with the way the Addon was built but trust me there's really no issue. There can be multiple settings (from other addons or just Firefox settings) that can mess up what I tell the browser to do.
That's why I added the "Reverse restore order" feature in the Options. Please check that one to see if order will be preserved.
The addon knows to open even more than 10000 tabs, but depending on the number you want to open I'm not really sure if Firefox can really handle it (more exactly if the PC hardware can handle it the correct way). The thing is, if there's really a bug in the way Firefox opens 100 tabs when I tell him to do that I can't really do anything about that.

Anyway, I will investigate this again, but there's simply nothing wrong with the addon, I do what I must (I mean.. really... I go through every single tab and request Firefox to open it... it's not like I can't really do it properly), but if tabs are not opened then I probably have to check if there's any limitation regarding what the addon API can do, or if Firefox might miss some messages from the addon and I will try to find some workarounds.

Regarding your request to show the number of tabs next to each session. Yes, sorry about that, I will try to land it in the next update (the feature is planned but I kind forgot about it).

Regarding the rating, please have in consideration that there are extremely few people that really have hundred of tabs opened and restored so even you if are totally right the review might not be in line with most of the users. I really try to improve it constantly and even if I do something wrong I try to fix it right away. Having support from the community it's what drives me to continue to improve it :). Issues are fixable, but sadly bad ratings remain no matter what I do :(. No, I'm not asking to change your review, I just wanted to point out that it may not be a very accurate review for whoever intends to use the addon in the future.

Update
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I updated the addon. The new version should not have the same problem. I'll try to add more advanced feature in next releases to make sure that storage can't be deleted by such an error.
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I'm really really sorry about the issue. I think I found a problem related to why history session might disappear suddenly and I will try to have a fix today, or later tomorrow. I really appreciate that you didn't go straight to 1 star and I promise that I will do my best to fix it as soon as possible. Will update this comment once the fix is ready.
Sadly I discovered after I launched the addon that addon storage seems not to be that reliable, having in mind that even by reinstalling the addon you can lose everything. I think I will add a form of secondary backup (or even some form of manual backup) to make sure things are more reliable.
I know many people rely on the auto-save function but the addon is mainly developed for manual saving of sessions as bookmark. I kinda made the wrong decision to provide an auto-saving feature at some point and sadly that created a lot more problem than I expected.
Again, really sorry, I will do my best to make sure things like this can't happen again.

Yeah, sadly once the addon API changed Mozilla removed the possibility to store additional data alongside a bookmark and all the functionality that was based on that (pinned information, and other tab session information) was no longer going to work. I do have a solution in mind to provide this back, but sadly it's not something that can be as reliable as bookmarks and I'm not really sure if on the long run is not worse to implement something that may work only until you delete the addon and then just lose that data suddenly because it was saved in addon storage.

Regarding the "click cancel". Well that's not really what it happens there but I get why you thought that. That dialogue it's actually meant for you to edit the name of the session (which is already saved) so basically clicking cancel will just leave the session with the default name. The same edit box will show if you just go over any other session and edit it's name. I totally missed that it an create confusion if I show the edit box right after saving a session, that's a great observation and I'll think about it if there's anything that ca be done to improve the experience so that saving steps may be more clear. So this is not really a issue... everything works as it should... but I will think about the whole saving process to see if there's anything I can improve to be sure things can get confusing.

I'm not really sure I do understand the 3'rd statement :
"And it would be great if there was an option to manually save session in bookmarks or, like autosave session, in sqlite database in addon data storage folder."
So, saving in bookmarks is manually... or you wanted to say automatically save ?
Regarding addon storage... well that's seems to be problematic since it's not really reliable. Addon storage is there only if you have the addon installed. If by mistake (your or because of Firefox) the addon is removed, add the data associated with that specific addon is deleted right away. For example this is what happenes with the auto-saved sessions, they are simply deleted by Firefox when the addon is removed. So storing anything valuable in addon storage it's not something I can do right now , probably after I add some form of full backup, but even then it seems to me that the addon storage is really good for nothing because it give users the apparent idea that data is save but it's just isn't.

If you have any other feedback you can contact me directly over email (use the Feedback button from the addon menu) or if you have any feature request (or issue) you can also send it to https://github.com/ReDEnergy/SessionSync.

Thanks for detailed feedback (and for using the addon)

Hi and thanks for the review.

The thing is I didn't add a delete option the the "Active snapshot" because basically once the auto-save timer is triggered everything will be rewritten so deleting something from there can only work for as long as the auto-save timer is not triggered.
Now... I seriously should add the option to delete some other stuff... like closed windows from there because they can keep stacking up and there's no way to remove them right now.
Also I can definitely add the option you're talking for all the other saved sessions from the History Tab since there those will not be changing at all and you should be able to do whatever you want. I will let it available for the "Active snapshot" as well.. just in case someone wants to save things right after deleting a saved tab but as I was saying if the re-saves is triggered during that time... everything will be there again and I can't really do something about it.

Drag-n-drop was not implemented fully for History sessions but I will try to add support for as many things as possible even there.

Will try to implement this as soon as possible. If you remember about it when using the addon, I hope you will remember about this review as well and update it if it really becomes "a five-star extension" :)

Thanks for using the addon.

** Update **
Thanks for all the details. I will try to add the save and close feature in the next update. There will be 2-3 configuration settings to check for it initially to make it as you wish since I still need to consider everyone's ideas when implementing this but as long as it's a one time thing should be fine.
Regarding the sidebar... that requires a lot UI restructuring and that might take some time but I would consider this as well for future updates. Thanks.

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Can you please provide more information about how would you expect the addon to work when all tabs are closed ? All tabs from the current session or all windows and just leave one window (in case the session saves all windows and not just the current one). There's a thread here (https://github.com/ReDEnergy/SessionSync/issues/33) related to this issue, maybe you can provide your idea as well so that I can have multiple input on how to solve this.
I put tooltips for the toolbar menu but I suppose that you still need to move over them to understand them exactly what they do. Sadly, Firefox limits to 800 px the width of the addon so I can only put there labels for a few actions before I'm left with no space and that's why I used only icons. But, It's planed to have an option to also show the text along the icon, or only the text. I will try to provide this option as soon as possible.

So, If i fix those 2 issues then would you consider it a 5 star addon? Isn't there anything else? Because it's kinda hard for me to get how these only 2 issues make the addon a 3/5 star. I know it's hard to please everyone, but just think that it usually takes a lot of time to develop such an addon and the only reason why a developer would continue it is because there are users that support it, not financially, but by understanding that even if it's not perfect it can be improved. Of course, don't get me wrong, I'm not asking you to change the rating, but only to consider that low ratings can really hurt addons on the long run and are not really helping their development. Yes a review is also personal, it doesn't have to reflect everyone preferences, but it's really hard for me as a developer to add support for everything from the start. In time I might be able to do so but community support is valuable. Got a lot of request and ideas from users (https://github.com/ReDEnergy/SessionSync/issues) but implementing all of them is really challenging because many can be contradictory or were never in the original scope of the product.

Hi. Thanks a lot for review. I really have no idea why I didn't think about that. I will add an option to do that in the next release. Probably using a context menu I will be adding more common features for interacting with open tabs.

Thanks a lot, as for the question,
Yes. I had consider it. There are a few users that sent me some feedback on this.
Sometimes the way you design certain feature may prevent you to be able to add some other simple features like you describe.
The addon let's you open tabs from multiple sessions. And I have no good solution for tracking which tab came from which session (and it's pretty had to implement one as well). My point is... if you want replace the current session, do you want to save the "session" that will be closed automatically ? Because if you don't then I can do that pretty easy. But if you do want that... then I have no idea what tab and where I should save... Can't replace the session, can't save them as a new session... i can't seem to find a good solution for this. Also, what happens if you have multiple windows, and so on.
Truth is.. you can take 2 people and ask them how do they see a certain feature and chances are they won't expect the same outcome because each individual person has it's own way of interacting with windows/tabs and the concept of session my be different, etc. Any new feature I add I have to think about how exactly I can cover most of the use cases and sometimes it's not really easy to do that.
My solution for this is basically... I will try provide to multiple possible solution but I need to first implement a configurable toolbar so that people can hide buttons that will never want to use or use extremely rarely, and have those be available in a hidden dropdown list to the right of the toolbar.
Thanks as well.

Hi,
1) As of right now the addon does not let you search through all the bookmarks. Only those that you save or add inside the (Bookmark Menu -> SessionSync) folder. If you look in the bookmark manager you can see the folder there. By Advanced Bookmark Manager I meant that the addon can be used with that purpose in mind because you can manually save every tab, group of tabs, order them, edit, delete, etc but only if you do this through the addon UI.
2) Automatically saved sessions (those from History Tab) are not saved in bookmark because that might cause performance issues. Saving is done manually when you need to save something. I would say that the addon fits perfectly somewhere in the middle of an Bookmark Manager and a Session Manager, because it's mostly intended to have good control on what you want to do, and offers a very common Bookmark Manager experience, as well as because all the saving is done in Bookmarks.
NO, as long as you have Firefox Sync enabled (or whatever bookmark syncing solution you might use) all your bookmarks will be synced. Like I mentioned, all your Bookmarks are saved in the [Bookmark Menu -> SessionSync] folder so of course you will be able to find them there and interact with them even if you don't have the addon installed. For example that's what I do on my mobile phone. I access them through the Firefox mobile boomark manager because I don't a mobile version yet, but I can still access all my saves very easy.
3) In the addon panel you have a search bar in top-left. Or simply after you open the addon panel, press CTRL + F and then start typing. Search only works for folder names at this moment (sadly). If you want to search through Bookmarks... for the moment the Firefox URL bar can do that ... yes you will search through all the bookmarks not only those saved by the addon but at least it works.
In case you didn't seen the Tutorial, please look over it because it might explain a lot of the addon features (with images also). The tutorial can be access from the addon menu (top-right button from the addon-panel)
If you have other questions regarding the functionality you can also contact me over the mail. Just press on the "Send Feedback" button from the addon menu and the mail application should open with my address already completed.

Thanks for feedback

------------- Later edit ---------------

Thanks a lot for providing more details on the requested feature. Now I understand what do you mean by right click on the tab and I think it can be a very useful feature. I will definitely try to see how I can implement this using only the context menu. Not 100% sure it can be done but probably I can do something about it. If the API let's me get the multiple tab selection (from when you SHIFT select many tabs) I will try to add support for it as well.
Many thanks for giving me another star :). I really appreciate it.

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Hi. You can drag-n-drop any tab to another Window group (active window) and reorder them. Yes you can't drag a tab into a certain saved session but that's a wonderful idea and I can definitely implement it very fast. Multiple tab selection is not that easy to implement but I have it planed for a later update.
If you consider to provide a better description of the feature you want please send me an email (through the Feedback button from the addon-menu) or submit a new issue on Github.
Probably it's better to also take a look over all the features that I plan to add just to make sure that what you want is not already planned. https://github.com/ReDEnergy/SessionSync/issues/40
Thanks for trying the addon, and when I will have all those features that you want implemented please remember to come back and reconsider the feedback.

Thanks for the review. Although it's more of a bug report. But at least you managed to give me the answer why for some people the restore is in reverse order. I tested it and it's exactly as you say. Sorry about that, but I really had no idea about it and thus it was impossible for me to find you where and why the bug happened. Now that I know, I can definitely look into it to find a solution. Hope you would consider rising the rating If I will fix it (after the update of course).
Thanks for using the addon.

Thanks for the review. Just used translate to understand the review :D (sadly I don't know Chinese). 谢谢