Ggltf

This addon is highly specialised in exporting assets into game engines using glTF file format. It achieves that by giving the user access to a library that does most of the heavy lifting and a very fast way to run your code via buttons minimising time between exporting and seeing new changes within the game engine.

Have a look at the features and limitations section below to see if it fits your purpose, if you do not need any of this functionality I highly advise you to stick to the default glTF exporter.

Otherwise get started here.

Features

Additive workflow, start with nothing and add only what you need.
Non-destructively merge multiple meshes into one.
Add as many UV maps, vertex colors or shape keys to your meshes as you need.
Break down your complex scene into smaller files.
Easily add hierarchies, collections or singular objects.
Non-destructively remove objects with with filters and blacklists.
No glTF scenes required, making it possible to create asset libraries (for example file containing only meshes).
Non-destructively strip bones from armatures with filters and blacklists.
Automate excluding useless control bones and trimming bone prefixes when using rigify armatures.
Use timeline markers, manual frame ranges or NLA tracks to bake animations.
Manually specify which NLA tracks are to be grouped together into one animation, allowing for the use of additive tracks.
Force animation to be use stepped interpolation.
Easily create buttons to run your code from outside of the text editor.

Limitations

Cannot export base meshes, each mesh has to be assigned to an object in scene in order to be exported.
When merging meshes, UV map, vertex color and shape key names must match.
Meshes can only be based on blender meshes, no curves, NURBS, etc.

This addon is still a work in progress, and does not support all data types: