Actually, you can now! We’ve developed a free script for After Effects that exports GIFs in 1 click. It’s called AEJuice GIF. You can download it and learn more at this blog post https://aejuice.com/blog/how-to-make-a-gif-in-after-effects/?utm_source=creativecow_comment
After installation, go to Window – AEJuice GIF.jsxbin (on the bottom). Open a composition, press Render in the script. It will export a GIF animation and open it after a render.
One note, the installer will only search for After Effects CC 2015 or higher but the GIF script should work with CS6. You might need to manually copy the AEJuice GIF.jsxbin file from the C:\Program Files\Adobe\Adobe After Effects CC 2015\Support Files\Scripts\ScriptUI Panels to C:\Program Files\Adobe\Adobe After Effects CS6\Support Files\Scripts\ScriptUI Panels folder.
You should be good to go with default settings but in case you’d like to customize here are a few settings I change:
Export folder – by default, it’s your project’s folder but you can export all GIFs to a custom folder.
Loop – by default, all GIFs loop forever but you can loop it once, twice, etc.
Alpha channel – by default, it’s off but sometimes you might need a transparent background.
Comps\Folders – sometimes you might need to export a lot of compositions at once so you might need to switch to the folder from compositions.
Change width – this one is rarer but I use it sometimes. It will change all auto-resize to the specified one.
There are a lot of advanced settings but I never use them.