Do you count custom storage space toward plan's quota?
No. We count only storage space taken by your files in Uploadcare storage. If you connect a custom bucket, copy uploaded files to it, and then delete them from Uploadcare, we won't count storage usage. Please, notice that in the custom storage workflow, Uploadcare storage acts as transitional storage. By default, it stores your files permanently, so you might need to either disable the auto-store option or delete files from Uploadcare after they are copied to your bucket.