Update: 21-09-16

Figma

@A04V4NK4E-figma

Figma is a collaborative interface design tool. Our aim is to combine the power of legacy programs like Illustrator with the collaborative flexibility of web apps like Google Docs. You can do vector-based UI design, editing, commenting, sharing, and storing all in one place -- in the browser. When you connect Figma to Slack, you are able to create a shared team space and maintain a directory of team files that is constantly up-to-date, with version history for every file.
Anyone with access to the shared space can access and comment on files. Only people within your Slack team can ever see files created in the team space, adding extra security to files. Within the team space you can also share components, such as a color library.
You can also configure the integration to notify channels on updates to your files.