.ESM

.ESM file extension

This is the basic program to work with .ESM extension

TES Construction Set

TES Construction Set Morrowind Master Data File

The Elder Scrolls Construction Set allows you to edit and create any data for use with The Elder Scrolls IV: Oblivion. Any data that goes into the game goes in through the Construction Set and is stored in data files (labeled either ESM or ESP files) that are read by the game... (more)

The program works with the following extensions: esm, esp

.ESM extension is also supported by the following programs:

PhotoLine

PhotoLine PhotoLine Document

PhotoLine can help you edit and convert your pictures.
Fallout 3 - The Garden of Eden Creation Kit

Fallout 3 - The Garden of Eden Creation Kit Bethesda Master Data File

The GECK is used to create game content for Fallout 3.