Before I start I'd like to mention that there is already an inventory editor for Terraria here, on Gamebanana, but I prefer this one for a couple of reasons. TerrariViewer is more visually appealing in my opinion. Also, TerrariViewer includes pictures. Also, you can create a new player right then and there.


Description:
TerrariViewer is a goon made character and inventory editor for Terraria.
Currently, TerrariViewer allows you to edit your players Name, HP, Mana, Hair, Character colors, Armor, Accessories, Inventory and Piggy Bank. You can also randomize your characters colors and hair by click on their respective Randomize button on the Character Editor page.

I did not create this tool, and I am not sure who created it.
Check out this inventory editor for Minecraft!