How to useThis tool can edit items and statements on Wikidata, based on the content of a category from Wikimedia Commons. It is chiefly designed with art items in mind, and might not be appropriate for other themes.
First, specify a category from Commons in the text box above. The tool parses it, gets infos from Wikidata if needed, and displays images. You may then select them and edit statements in the right panel: if an image is already linked to a item on Wikidata, statements will be added to this item (existing statements are displayed but can't be modified); otherwise, a brand new item will be created for your statements to be added to. You may select several images at the same time (while holding the shift or control keys) and perform bulk edits.
When done, press the QuickStatements button on the top right. This will open another page to QuickStatements, another tool that can add statements to Wikidata items. (I'm lazy, so I'm outsourcing edits; Wikidata isn't modified at all when you're using my tool.)
Keep in mind this tool is still very much in infancy: bugs are most likely to happen.
Everything on that page is under the Creative Commons Attribution-Sharealike (BY-SA) license. Infos, help, rants can be directly expressed to Poulpy.