What are some alternatives?
When comparing Akira and Sketch, you can also consider the following products
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
Icons8 Lunacy - Free graphic design software with built-in resources. Fully compatible with Sketch and works offline
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
Affinity Designer - Professional creative software, exclusively for Mac.
Alva - A radically new digital design tool built for cross-functional product teams