See also: tEdit Wiki.

tEdit is an open source world editor with Paint-like functionality. It allows advanced features such as copy-and-paste, liquid placement, and block placement.

Terraria - Mod Feature - TEdit 3

Terraria - Mod Feature - TEdit 3

Installation and Use

  1. Back up your world and player files.
  2. Download the program and place all of the files in a folder.
  3. Run the TEdit executable. On the menu, go to File>Open.
  4. Navigate to Documents\My Games\Terraria\Worlds. This folder contains your world files, which are opened directly using tEdit.

Old link

TEdit for 1.3

BinaryConstruct has released an official betas of TEdit for 1.3, downloadable from here. These beta releases are interesting due to their inability to run. Upon launching such a beta of TEdit, a window is created with version in the title, then the program freezes after allocating 50MB or so of RAM. Kaspersky anti-virus products will declare these betas to be a trojan, likely due to the inability of the betas to function "properly" in lieu of how a trojan works. All other major anti-virus products find these betas to be safe.

The official author of TEdit, BinaryConstruct, had not yet completed and/or released TEdit for Terraria 1.3 prior to mid August, so several unofficial forks popped up for 1.3. They have mostly complete functionality, but being experimental, they should be used with caution. Manually back up any worlds you wish to edit beforehand, and use TEdit with the same wariness that one might have while sneaking through the lair of the sleeping Moon Lord.

RECOMMENDED: Download a more recent and updated fork by SBLogic here.
You can download first fork by speeder here.