When comparing Notepad++ vs P4Merge, the Slant community recommends P4Merge for most people. In the question“What is the best tool for resolving conflicts when merging file changes?” P4Merge is ranked 3rd while Notepad++ is ranked 8th. The most important reason people chose P4Merge is:
P4Merge is free of charge.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Syntax highlighting for a wide variety of languages
Notepad++ has built-in support for syntax highlighting for a wide selection of programming languages.
Pro Light and fast
Notepad++ is a very light program that starts almost instantly. This makes it a great text editor for users that want something that will start the second they open it.
Pro Extendable via plugins
A list of hundreds of plugins is maintained.
Pro Portable
You can get a portable version of N++ and put it on a flash drive or your dropbox account and have your editor, configured the way you like, at any computer that you are on.
Pro Free under GPL
Notepad++ is licensed under GPL, which means it is free/open source software that you can use freely.
Pro Regex replace in selection, active tab, or all tabs
In Notepad++, the user can utilise regular expressions to quickly modify text across multiple files.
Pro Persistent documents, even after exiting the application
If you close Notepad++ (npp), your documents remain even if you haven't saved.
Pro User defined language syntax support
You can define your own custom syntax highlighting rules (or add support for others) .
Pro Easy to use and admin
Very easy to use and personalize.

Pro Multi-line editing
While it is disabled by default, when enabled, it is possible to edit more than one line at a time. This is helpful in many situations.
Pro Split screen
The user can open and edit files in multiple screens within the editor window.
Pro Supports Markdown
If you have the Plugin Manager installed you can search for MarkdownViewer++ and install it via that plugin.
Pro Free
P4Merge is free of charge.
Pro 3 way merge support
P4Merge presents merge information in 4 panes - BASE, LOCAL, REMOTE and MERGE_RESULT.
Pro Detects minimal changes without having a common ancestor
After a merge sometimes you have conflicts. You can resolve them by using a merge tool. You can run git mergetool --tool-help
to get more details about what tools are supported.
You will get an output like the followinggit mergetool --tool=<tool>
may be set to one of the following:
p4merge
tortoisemerge
vimdiff
vimdiff2
vimdiff3
The following tools are valid, but not currently available:
araxis
bc
bc3
codecompare
deltawalker
diffmerge
diffuse
ecmerge
emerge
gvimdiff
gvimdiff2
gvimdiff3
kdiff3
meld
opendiff
tkdiff
winmerge
xxdiff
Some of the tools listed above only work in a windowed environment. If run in a terminal-only session, they will fail.
Pro Also has image diffing
For those who are working in both text based source code or files, as well as images, its nice to have the diff functionality of both present in the same product.
Pro Cross-platform with a good Mac port
P4Merge works on Windows, Linux and OS X.
Cons
Con Windows-only
While it can run in Wine, it is native only to Windows. Linux users will have to use Notepadqq instead.
Con Settings confusingly scattered
Examples: try to change the tab size or used font.
Con Annoying update notifications upon start-up
Annoying update notifications tend to pop up upon start-up after not having used the app or machine for a few days. At the same time, they can be easily turned off.
Con Outdated UI
Only the text area can be themed, and it doesn't have as many features as browser-based text areas.
Con Limited new syntax support for new languages
It may be hard to find good plugins for relatively new languages.
Con Session backups not enabled by default
Unsaved tabs will be lost when Npp crashes, unless you first enable the session backup option.
Con User defined language doesn't support triple quote strings
It also doesn't support triple hashed comments. Both styles are overridden by their single character single line version.
Con Directory comparison is not supported
With P4Merge it's impossible to compare two different directories to find differences.
