Create Glowing Text using Gimp

Type Glowing Text (White)

Right click Text layer-select Layer to Image size.
Right click Text Layer, Select Alpha to Selection, next Click Select-Grow (3).

Duplicate layer. Fill Text Color Purple. Select none. (Name this layer as GLOW)

and move below Text Layer.

Filter Blur-Gaussian Blur (45)

Duplicate Layer, Set Gaussian Blur to 30.

Duplicate layer and set Gaussian Blur to 15. Next Set Layers mode to Dodge.

Duplicate Layer (GLOW) and move it to the top of all layers, set layer
mode to Dodge.