The Figma App Design Workflow - online tool.

The development team come with this intro:
Figma is the first interface design tool based in the browser, making it easier for teams to create software.
The Figma pricing start with:

• Basic - free for individuals 
• Professional - $12*
• Organization - $45*

You can start with your your email or google account, see first page:
The interface is simple and colors are great.
The official youtube channel come with many videos about this online tool.
You can find any references and tutorials on web.
The CharliMarieTV channel come with this title about Figma : Sketch vs Figma - Why I switched!