Boiling water. just don't burn yourself.
vinegar
pulling the weeds.

@TownHubAdmin : Cannot remember what items they are. But I did hear about some years ago that are natural pesticides & herbicides.
Also, many items we call weeds are really herbs. So many plants in our yards are edible and can make healthy teas from.

We hand weed our yard and for decades have not used any chemicals in our yard or garden. Still healthy and green as ever.

I quit using chemicals when I had a dog turn up with lymphoma.. no problems like that since.. and it just builds up when one critter eats another.. I use all organic now.

Mixing in a surfactant helps herbicide stick to the leaf and will get a better kill rate. You can buy it or just use some dish soap mixed in the tank.

@msuz : True, but they make Weed and Grass Killer too.