Tes3Mod:Wrye Mash

Wrye Mash is a general purpose utility for managing and repairing mods and savegames. Currently it is the only tool that systematically prevents doubling. It combines multiple mod-management capabilities making it one of the most strongly recommended utilities for both modders and players. There are now several versions from which users may choose. All offer the same functionality for handling installer packages, mods and savegames through a GUI (With the exception being the Wrye Mash GitHub Fork by Sharlikran and Wrye Mash 2018 fork by Polemos which have more functionalities). A tutorial (in pdf format) is available from vermin.

Versions
Original
Version: 0.84 [2/5/2009] Updated rarely.
Author: Wrye
Download:  
Readme:  
This version requires a download of python and wxpython. An installation tutorial can be found at the UESP Forums.
For those willing to edit python, this version still offers the greatest customizability. An example of integrating external utility functions into the GUI is available from abot's edited file.

WMSA
Version 0.0.3 [2010.11.6]
Author: Melchor
Download: WMSA
This is the first standalone version. This version introduced the 'Utilities' tab, allowing the user to call up programs from the Wrye Mash GUI.

Wrye Mash Fork
Version: 2011.05.11, 2012.01.05-dev
Author: Yacoby
Download: Wrye Mash Fork
This is the latest standalone version.

Wrye Mash Fork Python  version
Version: 2014.08.31
Author: Yacoby
Download: Wrye Mash Fork
This is the latest Yacoby's not-standalone version. It should be more compatible with new Python versions, contains a couple of fixes after 2012.01.05 release and offers same customizability as Wrye's original because of not being compiled into standalone executable.

Wrye Mash GitHub Fork
Version: 87 Beta2 [Under Development]
Author: Sharlikran
Download: Wrye Mash Releases
Homepage: Wrye-Code-Collection
This version has various bug-fixes and Unicode updates. Most of the testing for the Unicode changes has been done by Leonardo. He has a Swedish environment that is great for testing. There is a compiled EXE but you can also obtain the latest Python code. The current Python code may contain changes not in the latest standalone EXE.

Wrye Mash -Polemos fork- 2020
Version: 101beta 4/2020
Author: Polemos
Download: Morrowind Nexus
Source: Github
Homepage: Morrowind Nexus
This standalone edition of Wrye Mash is based on the latest Yacoby's source. The "editing the file header" bug is fixed and retains all the extra functionalities like drag and drop. It has mlox and TES3cmd support and many new features like: A toolbar menu, mod order snapshots, TES3lint support, BSA Archives support, UNICODE support, MWSE support, animation package support and much more. Tested in WinXP, Win7 x64 and Win 10. The author is currently also working on OpenMW and for implementing support for TES3MP.

Wrye Mash for OpenMW
Version: v101 alpha 4/2020
Author: Polemos
Download: Morrowind Nexus
Source: Github
Homepage: Morrowind Nexus
Wrye Mash for OpenMW (soon also for TES3MP). A stand alone edition of Wrye Mash Polemos fork (same code base), but configured for OpenMW by default. Still in alpha stage so missing a lot of features.

Installer Packages
Install and uninstall mod packages through a simple interface. No need to manually track the files belonging to different packages.
Easily view resource conflicts between packages.
Includes a 7zip dll allowing installers to remain in a compressed format, automatically uncompressing when the user installs the package.

Mod Management
Select, reorder and rename mods.
View mod readmes.
Label mods by Group/Genre (e.g., Fix, Weapon, NPC, Quest, etc.)
Sort mods by: Name, Date, Load Order, Size, Group/Genre, Author.
Backup, duplicate, snapshot, hide/unhide mods.
Merge and resequence leveled lists.

Mod Repair
Repair mod references.

Mod Editing
Edit Author and Description fields.
Edit masters list.
Copy esm to esp and vice versa.
Sort records.
Review
File statistics.
Export/Import 
Dialog. (Formatted to ease spell checking and revising.)
Living Cities of Vvardenfell style schedules.
Systematically replace references.
Users can define arbitrary ref replacers.
Necessities of Morrowind: replace statics and bottles.
Morrowind Comes Alive: replace placeholders with MCA spawn points.

Savegame Management
Load Masters (Set load list to savegame's master list.)
Rename, backup, duplicate, snapshot, hide/unhide saves.
Sort saves by: Name, Date, Size, Player Name, Cell.
Edit Masters List
Sync to changes in the load list.
Upgrade to a newer version of a mod.
Review
Journal
Map Notes
File statistics.
Remove/Reset
Creatures spawn points.
Bethesda creatures, doors, containers.
User defined lists of objects.

Savegame Repair
Repair All
Repair mismatched references.
Remove orphan contents.
Remove debris records.

Screenshots
These images display the latest Yacoby build (2012.01.05-dev). The Original from Wrye, Melchor's WMSA, Yakoby's Wrye Mash Fork Standalone and Python look the same and offer the same management and repair functions for installers, mods and savegames as described above.
The Wrye Mash GitHub Fork by Sharlikran and Wrye Mash 2018 fork by Polemos have more functionalities and a more modern look which are not shown in the images below.