Alternatives to Cairo Desktop
Open-source desktop environment for Windows that replaces the standard taskbar and shell. The listings below can replace it for an important use case. Each note says what changes if you switch.
The original
Cairo Desktop
Open-source desktop environment for Windows that replaces the standard taskbar and shell.
Replacements
Listings that take over the same core job as Cairo Desktop.
Seelen UI
Customize the Windows desktop with replacement interface components.
Seelen UI also replaces parts of the Windows desktop with configurable panels, launching and window-management features, and is open source under AGPL-3.0.
RetroBar
A replacement Windows taskbar with classic Windows 95, 98, Me, 2000, XP or Vista styles.
RetroBar replaces only the Windows taskbar, in classic Windows 95 to Vista styles, rather than the whole shell, and remains free and open source.
StartAllBack
Customize the Windows 11 Start menu, taskbar and Explorer interface.
StartAllBack customises the existing Windows 11 Start menu, taskbar and Explorer instead of replacing the shell, but it is paid and closed source.
ExplorerPatcher
Brings the Windows 10 taskbar, Start menu and Alt+Tab back to Windows 11, along with a lot of other interface options.
ExplorerPatcher patches Explorer to restore the Windows 10 taskbar and Start menu on Windows 11, is open source under GPL-2.0, and major Windows updates can break it.
Similar software
Related functionality, not a direct replacement.
Open-Shell
The continuation of Classic Shell, bringing a classic Start menu and Explorer toolbar back to Windows 7 through 11.
Start11
Replace the Windows Start menu with customizable layouts and organization.
TranslucentTB
Makes the Windows taskbar transparent, blurred or tinted, and changes it depending on what is on screen.
7+ Taskbar Tweaker
Change grouping, clicking and other behavior of the classic Windows taskbar.
SmartTaskbar
Hide the Windows taskbar automatically when it overlaps a window.
Rainmeter
Puts customisable widgets on the Windows desktop, from hardware meters and clocks to full audio visualisers.