How to export just one tag as a gif file

Since Aseprite v1.2-beta2 you can select what specific frame tag you want to export:

Other possibility is using the command line interface to export all tags:

aseprite -b player.ase --save-as player-{tag}.gif

Or just one tag using –frame-tag:

aseprite -b --frame-tag run player.ase --save-as player-run.gif