What are some alternatives?
When comparing karabiner-elements.pqrs.org Seil and SharpKeys, you can also consider the following products
Key Remapper - Intended for remapping keys, mouse buttons and mouse wheel actions, Key Remapper allows you to:
Karabiner - Karabiner, previously called KeyRemap4MacBook, is a very powerful keyboard remapper for Mac OS X.
xmodmap - The xmodmap program is used to edit and display the keyboard modifier map and keymap table that are...
Key Manager - ATNSOFT Key Manager, Key Remapper, Text Paster
X-Mouse Button Control - XMouse Button Control (XMBC) allows you to create application and window specific profiles.
Stick Shift - Stick Shift saves you time by removing repetitive changes to hand position when programming.