Hello!

Can anyone identify who is eating my seedlings? I've planted this bok choy twice and they end gobbled up by something, but i can't see any caterpillars, worms, slugs or aphids of any kind.

Any help would be great!
TIA,

ID'ing the culprit (and there are 100 + 1 possibilities) won't help you much, as there is nothing you can do about it short of turning your garden into a chemical wasteland.
Where I live, it is just about impossible to start anything from seeds sown in place. I must start seeds in pots in a protected place and then plant them out when they become large enough to fend off most of the seedling-predators. And I then still have to set up barriers for larger varmints such as birds, squirrels, rabbits, etc.

Everything loves cabbage. I cover mine with row cover and hold down the edges with bricks and stones to stop the nasties that want to crawl under. When they are seedlings I put some lumber next to the seedlings to hold them up off the plants. When they get bigger I just let the row cover sit right on the plant. It works pretty good, my first napa of the year is almost ready, I'll be making kim chi this weekend.

probably cut worms, but it could be anything really

Thanks to all @Frillylily, @Henderman, @kreemoweet. They are outside in a container (it's a roof garden garden), and the same has happened inside...I'm going to try again with sterile growing medium

You can use floating row covers to protect from pests. In the past, I also sprinkled cinnamon over the ground around my plants and it helped to keep certain pests out/make them go away.