Jake and Dan present a web app they created, Xnippit which is kind of like an online read–eval–print loop paste-bin where users can come to work on After Effects Expressions, and see instant visual feedback of what exactly you are doing.
Xnippet (expression snippets) and creates a visual representation of your expression as you type
With Xnippet, you are able to write expressions for After Effects in an environment more conducive for the task at hand.
Xnippet provides line numbers, color coded text, and instant feedback on what you are type as well as actual visual feedback on what the expression will be doing by way of a simple graph chart. You are even able to click and drag inside the graph and scrub through to see how the expression affects the output.
Once you have your expression complete in Xnippet, it will automatically create controls for all your variables that start with an underscore. With a completed expression you can save, store, or share your Xnippet After Effects Expression. What a wonderful idea! Check out Xnippet expression snippets web app for After Effects here.