A regular expression which in short is known as regex or regexp is also at times known as a rational expression. It is a set of characters arranged in a sequence that is used to form a search pattern and is used for “find and replace” like tasks. It is mainly used for pattern matching operations for strings and is used in theoretical computer science. This concept was introduced in the 1950s by an American mathematician called Stephen Kleene and is very extensively used in the UNIX operating system for its text processing utility called “ed” and the grep filter. Grep stands for global regular expression and a filter. Many commonly used commands on Linux operating system use regular expressions for find and replace type of tasks.
Regex are also heavily used for string manipulation operations like split and trim in Java programming language.
Below are some tools and websites that can help you write and test regular expressions much faster.
Regexr
It is an online tool which is used to build, learn and test regular expressions like the RegEx or RegExp. It helps in updating the results in the real-time as the user is typing the expression. You can also share the expressions or save it.
Regex101
It is an online tester for a regular expression like RegEx, a replacement tool as well as a debugger with capabilities for error detection and real time explanation. It can be used with languages like PHP, JavaScript and Python.
RETester
This online testing tool is used for testing the occurrence of the regular expressions in the target string and supports engines like .NET, Client side engine and Silverlight Tester. It has the facility of ignoring white spaces.
Rubular ( Ruby Expression Tester)
Rubular which is the abbreviated form of Ruby Expression Tester, is an expression editor for Ruby-based regular expression. It can be used to test the regular expressions real time as one is typing the regular expression.
Regexpal
It is a tool for testing regular expressions written in Java Script and has features like case insensitive, global and multi line anchors and Dot matches all. You have to enter the regular expression as well as the string to test in different fields for seeing the results.
Regexhero
It is an online .NET based regex tester and highlights the matches real-time as you type the regular expression. It also provides syntax highlighting for the regular expressions and generates code in C# as well as VB.NET.
Debuggex
It is an online visual tester for the regular expressions with the availability of a live text editor which is presently available in Beta version. It is a web application written in Javascript and so supports all modern browsers.
Regexplanet
It is a testing tool for online regular expression in the Java Programming language and uses java.util.regex.Pattern. It can be used for all known commonly used languages/engines such as JavaScript, Java, .NET, Pearl, Python and Ruby.
Regextester
It is a regex tester which is available online and can be used for languages like Python, PHP, JavaScript and PCRE. It highlights the matching patterns real time.
Freeformatter
This is a free tester for regular expressions which allows you to test the regular expressions against any entry as per the user’s choice and highlights all the matches found thereafter.
Pythonregex
It is an online testing tool which uses Python to quickly test the regular expressions.It considers the alphabets A to Z and the digits, the underscores and the digits 0 to 9 as word characters. It provides support for functions specific to Python regex as well.
Regexp
It is an online testing tool for regular expressions designed by the erik.eae.net where the user can key in the regular expression and the sample test to return the matching patterns. The tool ignores cases and allows multi-line entries.
Myregextester
It is an online tester for regular expressions that allows the online visitors to construct and test the regular expressions. It also allows optimization of the regular expressions entered. It highlights the matching patterns in the result area.
Regexr From Gskinner
It is an online tool which is used for editing as well as testing regular expressions like RegExp / RegEx. It provides a user-friendly interface for entering the regular expressions and shows real-time matches.
Expresso
It is an award winning online editor which is appropriate as a teaching tool for those users who have just started with regular expressions. It also can be used by an experienced web designer or a programmer with experience in regular expressions.
Regex Coach
It is a Windows based application for testing regular expressions which are compatible with the Perl Language. It tells you whether the regular expression entered is matching a particular string or not. Moreover, it attempts to explain the regular expressions in English.
Regex Larsolavtorvik
It is an online testing tool for regular expressions (regex) and supports Javascript, PCRE and POSIX. It has features such as multiple modes, real time highlighting and replacement.
Regex Tester From Gethifi
This regex testing tool from Gethifi uses Javascript for testing the presence of regular expressions using jQuery. The tool was designed by New Media Campaigns and is a powerful tester for web developers and designers.
Regex Tester From Gethifi
This regex testing tool from Gethifi uses Javascript for testing the presence of regular expressions using jQuery. The tool was designed by New Media Campaigns and is a powerful tester for web developers and designers.
Txt2re
Txt2re is a graphical regular expression (regex) generator which is available online. This tool allows the users to choose string components which are to be matched and generate corresponding regular expressions.
Regexpr
This function is used for the identification of the existence of a pattern within a character vector. Each element is tracked separately to identify the pattern. It is an online service for verifying the regular expressions.
Refiddle
Refiddle is an online testing tool for testing and generating regular expressions. It has great features such as ‘matching all occurrences’, ‘ignoring cases’ and ‘$ and ^ match each line’.
Osteele Rework
It is an online testing tool for the regular expressions designed by Oliver Steel. You need to type the regular expression to be tested in the “pattern” text box and the string in which the pattern will be searched for, against the regular expression you have input.
Regexe
It is a tool which allows you test a regular expression against the string entered for Perl or Java and see the results live, including the elements which have been captured.
PHP Regular Expression Tester
It is an online testing tool for regular expression used in the PHP language. It tests for the presence of regular expressions in a specific string entered.
RETester From Regexlib
Regular Expression Library provides a database which is searchable. The searchable database contains regular expressions. Users have the option to edit, add and test as well as rate the regular expressions.
JS Regex Tester
JS Regex Tester is an online testing tool which tests your regular expressions in JavaScript. The text entered would appear with a highlight on all the matching regular expressions. Once you enter the regular expression and the text, you can see the result in the result area.
Regexp Tool From FYIcenter.com
This online testing tool for regular expressions has been designed by FYIcenter.com and uses the PHP preg_replace() function. The user has to enter the string pattern and the string, followed by clicking the Start button.
Derekslager
It’s is on online testing tool for testing regular expressions in .NET. It is tipped to be a faster testing tool vis-à-vis the other testing tools on .NET which were available in the market.
Java Regex Tester
If you are looking for a regular expression tester for pattern matching in Java, Java Regex Tester is an ideal tool. The tool can highlight matches and replacements. The results can be displayed real-time.
Regex Coach
It is a Windows based graphical application which can be applied for testing those regular expressions which are compatible with the Perl language. It has feature such as displaying whether the regular expression entered is matching the target string or not. It also uses plain English to describe a regular expression. Development of this application is still going on so the website requests for donation towards the ongoing development costs.
Regex Buddy (Windows)
It is a Windows based graphical application which can be used to understand, use, create, test and last but not the least, save the regular expressions. The application makes it very simple to work with regular expressions.
Reggy OS X
Reggy is an open source C application for viewing and testing regular expressions in the OS X environment. It can visualize whether a regular expression is matching the target string very quickly.
QuRegexmm (Mac/Windows/UNIX)
It is an application for building regular expressions and is cross platform, supporting operating systems such as Linux, Windows, UNIX and MAC. It tries to find the regular expression in the target string and supports highlighting in multiple colors. It provides built-in support for wxRegEx and PCRE too.
Expresso (Windows)
It is an award-winning application which is used as a teaching tool for a beginner who is using regular expressions for the first time; it’s also useful for experienced web developers and programmers having detailed knowledge of the regular expressions.
RegexMagic
It is a useful application which helps in creation of regular expressions. Unlike tools like RegexBuddy which can only work with the regular expressions, in RegexMagic, the user does not have to be worried about the syntax of the regular expressions.
Dotnet Regex Tools
Authored by royosherove, this tool is an old version which was popular during the time when .Net was extensively used. The tool has been licensed under the Apache 2.
Regex is one of the most important tools in the toolkit of an experienced programmer. Regex tools are extremely handy, allowing a programmer to edit characters, text or patterns. Whether one wants to remove a punctuation or improve a website url, regex tools can always be deployed. In fact, the uses of regex tools are virtually limitless.