Can you bring backpacks to the top of the Eiffel Tower?

I think so.

I took a large shoulder bag (probably bigger than a backpack) to the second level of the Eiffel Tower two weeks ago. I had to open it for a security person to look inside, but tons of people had large bags, camera bags, etc. I didn't take the elevator all the way to the very top but I don't think you'll have a problem.

The backpack will be inspected by security, but you can bring it, if it isn't too large. The security people might look askance at a true camping backpack (some of which look as though they could hold a refrigerator), but I assume you mean the little ones that tourists carry.

Yes, I guess a "book bag" would be a better description. We're walking through the Rue Cler area on the way to the Eiffel Tower and we're going to be picking up wines, cheeces, breads, fruits, etc. and didn't want to detour back to the hotel to drop the stuff off. Thanks for the info.

Why not do the Rue Cler detour AFTER the Tower?