Pencil is an alternative to Sketch built from Electron.

Installing Pencil

Debian Way

Version 0.5.4~git20160219.9d29f33+dfsg-1ubuntu1 in Xenial

$ sudo apt-get install pencil

Download From Site

Version 3.0.0-rc1

Get the new one from http://pencil.evolus.vn/Next.html

$ wget https://github.com/evolus/pencil/releases/download/v3.0.0-rc.1/Pencil-3.0.0-rc.1.deb
$ sudo dpkg -i Pencil-3.0.0-rc.1.deb
$ sudo apt -f install

Done.