Once you’ve downloaded the latest version, extract everything inside the file! If the archive is not extracted you will lose any settings configured once the server shuts down. If you’re not able to handle that on your current computer, consider purchasing a Terraria server from a gameserver host. It does come with some system requirements, although nothing too over the top: You can download the latest release of TShock from their GitHub page or via their website. The easiest method is to add TShock to your server. Multiplayer item spawning will require the use of mods or plugins. Boot up your game and the items, buffs and any other changes you’ve made will have been applied to your save. Navigate back to your Terraria saves folder, and overwrite your save file with the new one you’ve just downloaded. This will download your save file with the edits you’ve just made. When you’re happy with what you’ve added, click the ‘Save Player’ button to the right of ‘Load Player’. From here, click the category you’re interested in or use the search function to find the item you want and drag it into your inventory. To the right of your inventory, click the Library button. Now you’ll want to click the ‘Inventory’ button to open up your inventory. After selecting it, your save will load into the app. This will open your Terraria saves, and prompt you to choose which player (.plr) file you want to edit. Once you’re on the site, click the ‘Load Player’ button in the top left. No need for downloading a third party program at all! Terrasavr is the easiest to use in my opinion, and it can all be done through the web app. In order to ‘spawn’ items in singleplayer you’re going to have to make use of a Terraria Inventory Editor.

Terraria 1.2.4 mobile guide