The downloads on these page are all for Windows. I do have a few Macintosh downloads, which I have listed seperately.
Blizzard released this demo late in August or early in September 1996. It allows playing the first two levels as a Warrior and fight the Butcher as a sort of end boss. There is no multiplayer, that was not yet part of the game concept. Some of the graphics are still different, and there are numerous spells that did not make it into the final game.
This is the best Trainer I could find. It works with all versions of Diablo up to 1.07 and Hellfire, and it also works with mods whose .EXEs have a different name, which is not the case with all trainers.
Most mods are made for Diablo version 1.07, and version 1.07 alone. So if you want to play mods, this is better what you'd have.
To save your finger and your mouse buttons while playing Diablo/Hellfire just use DiabloClicker2. This little tool sends mouse clicks to Diablo/Hellfire while the mouse button is pressed (left or right). The time between two clicks is adjustable in milliseconds. I have not tested this yet.
A small program with a wide variety of uses: Back up and move multiplayer characters, load mod DATs, play Diablo without the CD.
This utility backs up your multiplayer characters.
lets you view items, nothing more, nothing less. This is not an editor.
This little utility gives you the coordinates of all the items lying on the ground of the current map. It also gives you the position of your character, so you should be able to make some sense out of this information. Works only with newer versions of Diablo (1.07: yes. 1.00: no), works with mods.
There is no documentation to this tiny utility, no readme file, not even an about box. But none is needed. When started, it will simply show you what Adria, Griswold, and Wirt currently have to sell. If you wish, you can save any item as an .ITM file by double clicking on ithence Thief. Works only with newer versions of Diablo.
Most graphics in Diablo are stored in CEL or CL2 format. This program lets you view these formats, and it can read them directly out of the .MPQ file where they are stored on the CD.
This is a little utility that does exactly what its name says: Extract all the videos from the Diablo CD, including two that are not used in the game. This will give you ten files (some 64MB) with an .SMK extension. These are Smacker videos, a proprietary format popular in game design. To do anything useful with them you have to download the RAD Video Tools. Now you can not only watch them but also convert them to other formats or extract the frames.
The invaluable source about all the game mechanics.
The font used in and made extremely popular by Diablo. Many game sites use it.
A cautionary word in advance: You will not create another Netherworld with these tools. That requires some extensive hex editing and profound knowledge of the game. But you will be able to create your own monsters, weapons, uniques, and spells.