[JTyQZSnP3cQGa8B]

IIRC in theory it’s 2048 characters, but in practice it’s 2000 (at least in Chrome a few years ago when I toyed with Google Maps for food).

[hobs]

It's actually much longer, I was implementing a javascript bookmarklet and the old published limitations are not respected by much anymore, so you can shove a LOT of data in there.