A blog accumulates. Fifty posts in, the categories you started with no longer fit, half the archive was never filed at all, and fixing it means opening every post one at a time.
Bulk Blog Post Editor puts the whole blog on one screen with each post's status, categories and tags beside it. Filter to the posts you mean, select them, and add or remove a category or tag across the lot in one action. You can also publish, unpublish, feature or pin in the same way.
Posts that already have the category you picked are marked as such and left alone, so an action only writes the posts that actually change. The count on the button tells you how many that is before you commit.
One detail worth knowing: editing a post that is already live changes its draft, and that draft does not reach your site on its own. This app re-publishes those posts for you and says how many it is about to re-publish, so the version your readers see matches the one you just edited.
Built for the afternoon you finally reorganise the archive.