installation:

Steps as below:

1. Edit > Preferences > Add-Ons
2. Click the “Install…” button in the top right of the window
3. Find the Add-On file to install
4. Click “Install Add-on”
5. Check the checkbox to enable the addon. 

Addon preferences:

Preferences:

• Popover Width: the width of the Settings Panel
• Max Tabs Each Row: the max number of tabs in each row in the Sub Tabs Panel(also called Title Panel). But it has an optimization algorithm. For example, your Max Tabs Each Row is 4, and you have 5 tabs in one of your categories. It will display 3 tabs in the first row and 2 tabs in the second row, that is 3+2, not 4+1.
• Auto Apply On Startup: Auto Apply categories settings on Blender Startup. If you check this option, there's something to note. In some situations, the auto-apply does not work. For details, see the FAQ.
• Startup Delay: How long it will wait to apply categories settings after the Blender startup, counted in seconds.
• Exclude Tabs: The exclude tabs. This addon will ignore the panels of these tabs. After you change this field, you should restart the Blender.
• Show Sidebar: Whether to show the sidebar after applying categories settings.

Notes:

• The categories settings are not in the addon preference, but in the head of the 3D View.

Settings:

From version 1.1.2, the settings icon became the following one:

After installing and enabling this addon, the categories settings can be found here. They are not in the addon preference.

Categories management:

• Add new category: You can add a new category with this button. You can create a category to put similar tabs or workflow-related tabs. It is up to you. But don't use T as your category name, this is a reserved category name, this addon puts a lot of panels in this category. 
• Remove category: You can remove a category by clicking the cross button. Before deleting, it will ask you to be sure.
• Rename category: You can change the name of the category in the category name field. It has some verification, and if the new name does not meet the requirements, it will restore the original name.
• Fold/unfold categories: You can click the triangle button beside the 'Categories' to fold/unfold all the categories, and click the triangle button beside a certain category to fold/unfold a single category.
• Reorder categories: Clicking the Reorder Categories button, it will pop up a dialog with a list of all the category names. You can reorder the categories with the up/down arrow button. In here, we don't care about the details of categories, we just care about the category name in the order.

Tabs management:

• Add tab: By clicking this button, it will pop up a search dialog. You can choose the tab name you want to add.
• Remove tab: You can remove a tab by clicking the tab itself.
• Reorder tabs: With this button, you can reorder the tabs in the Sub Tabs Panel.

After you finish your categories settings, remember to click the Apply button on the top-right of the panel to apply your categories settings. It will update your sidebar.

Usage:

You can click the tab to enable/disable the tab. When you enable a tab, the other tabs in the same category will be disabled, and the panels of the disabled tabs will be placed in the temporary category(i.e. T category). A tab can be placed in multiple categories, but its panel will be only shown in the last category which enables it. If you find a tab in a category is enabled, but its panel is not showing. It can be placed in another category or the T category. You just need to re-enable the tab, thus it's the last category that enables it. If you still do not find the related panels in the category, you have to ensure you have enabled your related addon and meet certain conditions(for example, select an object or in certain mode, that's because some panels need to meet certain conditions to be shown). When you switch from one mode to another mode, for example from object mode to edit mode, some panels may not show in the category you set but in their original category. You just need to re-enable the tab. This addon will find it and put it in the category you set. For the same mode switch and the same tab, you only need to do it once in the Blender open session. Edit: from version 1.1.0, you can enable multiple tabs in one category by holding the Shift key.

About T Category:

After you apply/auto-apply the categories settings, the T category will automatically appear on the sidebar. It is a temporary category that stores all panels of disabled tabs in the categories. That is to say, this addon doesn't remove any of your panels. It just puts them somewhere else(i.e. temporary category). Generally, you don't need to pay attention to it. You just need to know what it is.

Issue about the Title Panel not at the top

Sometimes, the Title Panel(i.e. Sub Tabs Panel) is not at the top. It's possible that you changed the category settings and it wasn't applied, or you mis-dragged the order of the panels, or for some unknown reason. You just need to re-apply the categories settings or drag it manually to the top by dragging the eight-dot icon on the top right corner of a panel. By the way, if you change the category settings, remember to apply the category settings to update the sidebar. For more answers to the other issues, see the FAQ.

FAQ:

See it here.

Tips and Troubles shooting:

Tips:

• If you change the categories settings or import them from a file, remember to apply the settings.
• If you update the Exclude Tabs in the Addon Preferences, remember to restart Blender.
• If the auto-apply categories settings do not work on Blender startup, you can manually apply, they are the same thing.
• If you disable this addon, the categories settings will be lost. If you want to disable this addon and your settings are important, remember to export them in the addon references.
• In order to restore original categories or use another N Panel manage addon. Other than disabling this addon, you can just uncheck the Auto Apply On Startup option and not apply categories settings manually. This addon will do nothing to your sidebar, except for the HardOps and BoxCutter addons which may need you to modify their tab names in their addon preferences.
• Don't use T as a category name, it's a reserved category name. 
• About updating this addon and retaining the settings. The first method is to export the settings first, then remove the old version, and then install the new version, and finally restart Blender and import settings. The second method is to install the new version directly without removing the old version, and then restart Blender.
  

Troubles shooting:

• Most of the problems I encountered have been included in the FAQ, and you can see them here.
• If you have any trouble or feedback, please contact us.

Update:

version 1.1.3 (08/22/2024):

• Added the blender_manifest.toml file.
• Made some adjustments to make it more suitable for Blender Extensions. In addition, because the panels of HarpOps and BoxButter are some kind of special for this add-on, when they are changed to Blender Extensions form, we may need to make a little more adjustment. If you find that they are changed and there are some issues with managing their panels, you can report it to the maintainer of this add-on.

version 1.1.2 (07/23/2024):

• Made some adjustments along with the release of Blender 4.2.
• Changed the settings icon.

version 1.1.1 (02/05/2024):

• Fixed an issue about Auto Apply On Startup. And changed the default delay time after startup from 5 seconds to 2 seconds.

version 1.1.0 (01/19/2024):

• Filtered those panels that have no modules when applying categories settings/switching tabs. These panels are generally left behind by removed/disabled addons. No longer need to restart Blender when you remove/disable such addons.
• By holding the Shift key, you can enable multiple tabs in a category.
• Added a title panel to the T category to describe the T category. To dispel the users’ confusion about this category.
• Improved performance on applying categories settings and switching tabs.
  

version 1.0.3 (12/17/2023):

• Fixed a bug that occurred in the panels of the Dream Textures addon.
• Fixed the issue "Failed to unregister class ... missing bl_rna attribute ...".
• Modified some descriptions.

version 1.0.2 (12/03/2023):

• Max Tabs Each Row preference also apply to Settings Panel.
• Canceled the poll check when update panels(apply settings, switch tabs). That is to say, fixed the issue that some panels go outside the category you set when switch modes.
  

version 1.0.1 (11/26/2023):

• Cleaned some unnecessary test codes.
• Fixed a bug in importing settings.
  

version 1.0.0 (11/20/2023):

• First release.

Contact:

If you have any feedback or questions, feel free to contact us via the BlenderMarket's Ask a Question button. Thanks, Enjoy it!