No base plate. Stands up fine and is stable. I was hoping that was the case when I ordered it without the base plate.
I was going to test it by standing in it, but I might be a bit heavy for that. I think it would hold half my weight though.
I tested the stability by placing one of the loop legs up on the hearth. About an inch higher than the rest. It does tip slightly to the lower side and forms more of a diamond , rather than a square. I thought I would mess with footing to see if it would become unstable. I placed a shoe under one side, the other up in the hearth again. Not a perfect square , but still very stable.
With the loops/legs on uneven ground the fireplace may not form the perfect square for the iron grille to fit evenly, but I don't see it as an issue.
Honestly the base looks more like a good idea to catch any ash that might sift through the hinge points or the air holes around the top. I am sure it might add some strength in that the legs could not spread under weight, But I think they would still bend under my 200lbs
Now , I do not think I would want to try to move or relocate it once lit. the possibility of it folding up when lifted becomes a real possibility. That is where the base would be an asset. Moving it once it is in service would be too dangerous, IMO. I would rather quench and cool if relocation is needed. With the grille inside there is another piece helping to retain the form. It hold shape even better then. I might be a little more comfortable moving it with the grille inside. Still , cool of course.
This design is similar to a folding chair I used to have. You could wiggle around and get it to fold on you if you were not careful. I don't see the need for the fire to wiggle around much , so I hope it will be just fine.