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Regex Tester

Test a pattern live, with matches highlighted.

  • Free
  • No signup
  • Nothing uploaded
  • No watermark

Pattern

Flags

g i m s u y

What this pattern means
  1. \ba word boundary
  2. \w+a word character (letter, digit or _), one or more times
  3. @the character "@"
  4. \w+a word character (letter, digit or _), one or more times
  5. \.the character "."
  6. \w+a word character (letter, digit or _), one or more times
  7. \ba word boundary

Flags: g — find every match, not just the first

Test against

0 matches

Contact ada@example.com or grace@example.org today.

Replace with

Use $1, $2 for captured groups. Leave empty to skip.

How to Use the Regex Tester Online

Regex Tester: before and after TEXT A YOUR INPUT REGEX TESTER DONE A RESULT

Type a pattern and paste the text it should match. Every match is highlighted as you type, capture groups are listed for each one, and a plain-English breakdown explains what each part of the pattern does. Add a replacement with $1 and $2 to preview the result. The flavour is JavaScript, the one browsers and Node use.

A regular expression that looks right and matches the wrong thing costs more time than one that obviously fails. This shows every match against your own text as you type, highlights the capture groups, and explains what each part of the pattern is doing.

No software to install Free Works on any device

Step-by-Step Guide to Using the Regex Tester

  1. 1. Paste or type your input

  2. 2. Adjust the options to suit

  3. 3. Copy or download the result — it updates as you type

Try it now

What is the Regex Tester?

A regular expression that looks right and matches the wrong thing costs more time than one that obviously fails. This shows every match against your own text as you type, highlights the capture groups, and explains what each part of the pattern is doing.

At a glance

  • Takes: A pattern, flags (g i m s u y) and the text to test against
  • Gives: Highlighted matches, capture groups, an explanation, and a replace preview
  • Flavour: JavaScript RegExp — what runs in browsers and Node
  • Errors: An invalid pattern shows the engine's message instead of silently matching nothing
  • Limit: The first 500 matches are listed
  • Price: Free

Why Use Text Tools Online?

Counting words, changing case, pulling emails out of a page or writing an amount in words are small jobs that eat time by hand. These tools do them the moment you paste, and the text stays in your browser.

“Paste once, and let the tool do the fiddly part.”
  • Counts as you type
  • Lists sorted and cleaned
  • QR codes for anything
  • Cheque amounts in words
  • Case changed in one click
  • Emails and links pulled out
  • Citations in APA or Chicago
  • Handy commands for developers

Popular Uses for Text Utilities

Short, repetitive text jobs are what these tools were made for.

  • Essay word limits Check that an essay or application answer is within the word or character limit.
  • Fixing capital letters Turn text typed in CAPS LOCK into normal sentence case without retyping it.
  • Collecting contacts Pull every email address or phone number out of a long message or page.
  • Writing cheques Get a rupee or dollar amount written correctly in words for a cheque or invoice.
  • QR codes Make a QR code for a website link, contact card, email address or event.
  • Reference lists Format a book or website reference in APA or Chicago style for an assignment.
  • Tidying lists Sort lines alphabetically, remove repeats or add numbers to a pasted list.
  • Command helpers Build a cron schedule, git command or chmod setting without searching the manual.

What You Can Do with the Regex Tester

Matches as you type, against your own text

Explains why the input failed, not just that it did

Tests against the actual specification rather than a simplified pattern that rejects valid input

Why Use ToolXkit for Regex Tester?

Your files stay with you

Everything runs inside your browser. Nothing you open or type is uploaded to a server.

Writing and Text Tools for Different Users

Students

Count words, format citations and tidy notes before submitting coursework.

Writers and bloggers

Change case, find repeated words and check length before publishing a piece.

Office workers

Clean up pasted lists, find and replace names and write amounts in words.

Marketers

Extract emails, links and hashtags from pages and make QR codes for campaigns.

Developers

Encode Base64, build cron lines and generate git and shell commands quickly.

Accountants

Write invoice and cheque amounts in words and tidy columns of pasted figures.

Best Times to Clean Up Text

Text tools save time when you are:

  • Keeping to a word limit
  • Fixing text typed in capitals
  • Building a contact list from emails
  • Writing out a cheque
  • Printing a QR code poster
  • Finishing a reference list
  • Removing repeats from a list
  • Setting up a scheduled job

Tips and Good to Know

  1. Python, PCRE, Java and .NET differ in places — lookbehind, named groups, \d on Unicode. A pattern that passes here can still need adjusting there.

  2. It tests text you paste. For find-and-replace across a file on disk, build a sed command with the sed generator instead.

  3. Catastrophic backtracking will freeze the tab like anywhere else. Keep test text short while you are still shaping a pattern.

Frequently Asked Questions

Answers to common questions about this tool.

Which regex flavour is being tested?

JavaScript, because the test runs in your browser. Most patterns behave identically in Python, PCRE and Java, but lookbehind support and named-group syntax differ, so a pattern bound for another language is worth confirming there before you rely on it.

My pattern works here but not in my code.

Almost always the escaping. A pattern typed directly into this box is raw, while the same pattern inside a quoted string in your source needs its backslashes doubled. What you paste here is the pattern; what you write in code is a string that has to survive being parsed first.

Is my text sent anywhere when I use Regex Tester?

No. The text you paste is handled in your browser and never leaves the page. That makes it safe for drafts, customer lists and anything else you would rather keep to yourself.

Is there a limit on how much text I can paste?

The site sets none. Long documents are handled by your own device, so a whole book may be slow on an older phone. Articles, essays and long lists are no trouble.

Can I use Regex Tester without making an account?

Yes. There is no login, no email to hand over and no daily limit. Open the page, paste or type, and copy or download the result when it is ready.

Why does my word count differ from Microsoft Word?

Programs treat hyphenated words, numbers and symbols a little differently. The gap is usually a few words in a long piece. If a teacher or portal sets a limit, stay a little under it to be safe.

Do the QR codes made here expire?

No. The information is stored directly in the pattern, with no redirect through our servers, so the code keeps working for as long as the link or text inside it stays valid.

Further reading

  • Unicode Consortium The body that sets how letters, symbols and emoji from every language are stored as text.
  • Letter case (Wikipedia) The rules and names for upper case, lower case, title case and the styles programmers use.
  • Base64 (MDN) A plain explanation of Base64, the encoding used to carry files and images as text.

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