Multiple word search and replace in notepad++

Install Python Script plugin from Plugin Manager.

Create a file with your substitutions (e.g., C:/Temp/Substitutions.txt), separate values with space:

good bad
great worse
fine not

Create a new script:

with open('C:/Temp/Substitutions.txt') as f:
    for l in f:
        s = l.split()
        editor.replace(s[0], s[1])

Run the new script against the text you want to substitute.

I needed to run the substitution on several files.

So, based on Mauricio Morales's answer, I created the follow script.

with open('C:/Temp/Substitutions.txt') as f:
    files = notepad.getFiles()
    for file in files:
        notepad.activateFile(file[0]) 
        for l in f:
            s = l.split()
            editor.replace(s[0], s[1])
        f.seek(0) # reset file input stream

Try a regular expression replace of (good)|(great)|(fine) with (?1bad)(?2worse)(?3not).

The search looks for either of three alternatives separated by the |. Each alternative has ist own capture brackets. The replace uses the conditional form ?Ntrue-expression:false-expression where N is decimal digit, the clause checks whether capture expression N matches.

Tested in Notepad++ 6.3

Update:

You can find good documentation, about the new PRCE Regular Expressions, used by N++, since the 6.0 version, at the TWO addresses below :

http://www.boost.org/doc/libs/1_48_0/libs/regex/doc/html/boost_regex/syntax/perl_syntax.html

http://www.boost.org/doc/libs/1_48_0/libs/regex/doc/html/boost_regex/format/boost_format_syntax.html

The FIRST one concerns the syntax of regular expressions in SEARCH

The SECOND one concerns the syntax of regular expressions in REPLACEMENT

And, if you can understand "written French", I made a tutorial about PCRE regular expressions, stored in the personal site of Christian Cuvier (cchris), at the address below :

http://oedoc.free.fr/Regex/TutorielRegex.zip

(Extracted from a posting by THEVENOT Guy at http://sourceforge.net/p/notepad-plus/discussion/331754/thread/ca059a0a/ )

I looked around for some software that would replace several terms at the same time, Notepad ++ has a character limitation (limit of 2046 characters in the replace field), so I decided to make my own replacement version in HTML, here is the site:

https://jsfiddle.net/Byte/y50q1e7g/

window.onload = function(){
	$("textarea,input[type='text']").focus(function() { $(this).select(); } );
}


function replace(){
	
	// Get Configuration
	let separatedBy = new RegExp( $("#separatedBy").val() );
	let useRegex = $("#useRegex").prop("checked");
	let isCaseSensitive = $("#caseSensitive").prop("checked") ? "" : "i";
	
	// Get 'Find' and 'Replace'
	let find = $('#find').val().split(separatedBy);
	let replace = $('#replace').val().split(separatedBy);
	
	// Make result equal origin
	$("#result").val($("#original").val());
	
	// Run in each 'find' item
	for(i=0; i<find.length; i++){
		// check if not use Regex to escape the regex
		find[i] = useRegex ? find[i] : find[i].replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&');
		
		// Replace
		$("#result").val($("#result").val().replace(new RegExp(find[i],"g"+isCaseSensitive), replace[i]));
	}
	
}

*{
	font-family: Sans-Serif;
	box-sizing: border-box;
}

body{
	padding:1em 10%;
}

textarea,input[type='text']{
	font-family: monospace;
}

textarea{
	border-radius: 5px;
	width: 100%;
	padding:1em;
}

.config{
	width: 100%;
	border-radius: 5px;
	border: 1px solid #888888;
	padding: 1em;
	display: inline-block;
	color: #888888;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<p>
	Original text:<br />
	<textarea id="original" rows="4" cols="50"></textarea>
</p>

<p>
	Items to find:<br />
<textarea id="find" rows="4" cols="50">item1
item2
item3</textarea>
</p>

<p>
	Items to replace:<br />
<textarea id="replace" rows="4" cols="50">replace1
replace2
replace3</textarea>
</p>

<p class="config">
	<b>Configuration:</b><br><br />
	- Items separated by <input id="separatedBy" type="text" value="\n" size="3" /> (Regex)<br />
	- <input id="useRegex" type="checkbox"/> Use Regex in each item<br>
	- <input id="caseSensitive" type="checkbox" checked/> Use case sensitive
</p>

<p>
	<input type="button" value="Replace" onclick="replace()" />
</p>

<p>
	Result:<br>
	<textarea id="result"  rows="4" cols="50"></textarea>
</p>