What are some alternatives?
When comparing Extra Keys and AllChars, you can also consider the following products
Event Viewer - Get help, support, and tutorials for Windows products—Windows 10, Windows 8.1, Windows 7, and Windows 10 Mobile.
Holdkey - Holdkey is a Windows program that makes it easy to type characters with accents.
BabelMap - Unicode Character Map for Windows
Gucharmap - Open source character map for the GNOME desktop environment.
WinCompose - WinCompose supports the standard Compose file format.
SymbSearch - A tool for searching unicode-symbols and copying it to the clipboard.