Anyone have recommendations for a good toddler shoe that can be bought online with free returns?

DD2 is 16 months and has grown out of her soft-sole shoes she's been wearing. I'd like to move into something with a harder sole for backyard exploring. With DD1, I would take her to the store to have someone help professionally measure and fit shoes this young, but that's not so much an option right now.

I want to say we had several Stride Rite sandal-type shoes for my first but she's 7.5 now so it's been a while

What's your fave? And how do I figure out what sizes to buy and try?