You can now use HTML, CSS and javascript to create extension panels for Adobe Creative Cloud applications such as Photoshop, Illustrator and Premiere.
The following projects are free and open source tools and utilities to help you build those web standard based extensions.
A Brackets extension to easily create Creative Cloud extensions.
Start your extension from a selection of well formed templates.
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Command line tools to help you set up your system and deploy extensions.
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Sample extensions for various creative tools to get started with real projects.