Cryptomatte Tools allows easily to pick objects for Cryptomatte nodes or easily generate Color ID maps (the addon support even objects with Alpha channel), provides Python API and can help to export Cryptomatte as separate images (useful for importing to programs which do not directly support Cryptomatte)
With Cryptomatte Tools addon there is no need to manually pick objects in Compositor and it is possible to pick objects or materials even if they are not visible in current frame.
The addon can also help render Color ID maps for objects or materials, even if they use alpha channel, the addon supports shader transparency so Color ID pass will be rendered correctly even if for partially transparent materials.
The addon also keeps track of objects and materials in Cryptomatte nodes, and if you change object/material name, it will automatically update the Cryptomatte ID in all Cryptomatte nodes where it is used. It also offers automatic update of Render Result even if the Compositor is not open when adding or removing objects/materials from the active Cryptomatte node. And it is possible to append all objects from the active Cryptomatte node to selection (if selection is empty, it is a quick and easy way to see what objects are chosen in the Cryptomatte node).
Please watch the video to see it in action and how to use it. The video does not cover all features, only the basics. The video will be updated in near future to cover all recently implemented features but for now, please read the rest of this description and the documentation to learn about all available features.
The addon works with Cycles and Eevee (Cryptomatte for Eevee requires Blender 2.92 or newer).
If you are looking to automate things, Cryptomatte Tools implements Python API to get Cryptomatte IDs, add them to Cryptomatte nodes and do many other useful things (this video does not demonstrate Python API)
There is also a feature for exporting to programs which do not support Cryptomatte directly but can use separate images for each object/material.
Cryptomatte Tools (addon for Blender 2.83, 2.9+ and 3.0+)