Regex Replacer– Find & Replace with Regex

Find and replace text using regular expressions with group backreferences.

Pattern

Flags

Replacement

Input Text

Result

Why Use Our Regex Replacer?

Pattern Replace

Replace all matches with custom substitution strings using regex power.

Group References

Use $1, $2 backreferences to rearrange and transform captured content.

Instant Results

See the transformed text immediately after clicking Replace.

100% Secure

All processing happens in your browser. Data never leaves your device.

Full Regex

Supports complete JavaScript regex including lookaheads and named groups.

Free Forever

No signup, no limits. Replace unlimited patterns completely free.

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Complete Regex Replacement Guide

Regex find and replace is a powerful text transformation technique that uses regular expression patterns to identify text and substitute it with a replacement string. Unlike simple string replacement that matches exact text, regex replacement can match complex patterns -- email addresses, phone numbers, dates, URLs, and more -- and transform them using captured groups and backreferences.

Our free online regex replacer lets you enter a pattern with optional capturing groups, specify flags for matching behavior, provide a replacement template using $1, $2 backreferences, and instantly see the transformed result. This workflow is essential for batch text transformations, data cleaning, and format conversions that would be tedious or impossible with simple find-and-replace.

Common examples include reformatting dates (MM/DD/YYYY to YYYY-MM-DD), obfuscating email addresses, extracting and rearranging CSV fields, converting naming conventions (camelCase to snake_case), and cleaning up messy data from various sources. The combination of pattern matching and backreference substitution makes regex replacement one of the most powerful text processing tools available.

All processing happens locally in your browser. Your text data and patterns never leave your device, making this tool safe for processing sensitive or proprietary content.

The real power of regex replacement comes from substitution tokens that let you reference captured content from the match. Understanding these tokens is essential for effective text transformation.

Token	Meaning	Example
$1, $2, $3...	Content captured by the 1st, 2nd, 3rd group	Pattern: (\w+)@(\w+) / Replace: $1 at $2
$&	The entire matched text	Replace: [$&] wraps match in brackets
$`	Text before the match	Inserts everything preceding the match
$'	Text after the match	Inserts everything following the match
$$	Literal dollar sign	Replace: $$ outputs a single $

These substitution tokens work in all JavaScript environments and follow the ECMAScript specification. Mastering them unlocks sophisticated text transformations that go far beyond simple string replacement.

Reformat Dates

Pattern: (\d2)/(\d2)/(\d4) / Replace: $3-$1-$2. Converts MM/DD/YYYY to YYYY-MM-DD ISO format. Essential for data standardization.

Obfuscate Emails

Pattern: (\w+)@(\w+\.\w+) / Replace: [$1 at $2]. Converts user@domain.com to [user at domain.com] for display on public pages.

Add HTML Tags

Pattern: ^(.+)$ with 'm' flag / Replace: <p>$1</p>. Wraps each line of text in paragraph tags for HTML conversion.

Strip HTML Tags

Pattern: <[^>]+> / Replace: (empty). Removes all HTML tags from text, leaving only the plain text content.

Swap Name Order

Pattern: (\w+),\s*(\w+) / Replace: $2 $1. Converts "Doe, John" to "John Doe" format for data normalization.

Clean Phone Numbers

Pattern: $?(\d3)$?[\s.-]?(\d3)[\s.-]?(\d4) / Replace: ($1) $2-$3. Standardizes various phone formats to (xxx) xxx-xxxx.

Test before replacing: Use our Regex Tester first to verify your pattern matches exactly what you intend. Once confirmed, switch to the Replacer to perform the substitution. This two-step workflow prevents accidental data corruption.
Always use the 'g' flag for bulk replacement: Without the global flag, only the first match is replaced. If you want every occurrence transformed, include 'g' in your flags.
Keep your original data: Always work on a copy of your data. Regex replacement is a one-way operation. Having the original lets you verify results and retry if needed.
Use non-capturing groups when you don't need backreferences: (?:...) groups without capturing, keeping your $1, $2 numbering clean and only referencing the groups you actually need in the replacement.
Escape dollar signs in replacements: If your replacement string needs a literal dollar sign, use $$ to prevent it from being interpreted as a backreference token.

Following these practices ensures your regex replacements produce correct results and don't accidentally modify text you didn't intend to change.

How do I find and replace with regex online?

Enter your regex pattern, set flags (like 'g' for global), paste your input text, enter the replacement string (using $1, $2 for captured groups), and click 'Replace'. The result shows your text with all matches substituted.

What are replacement backreferences like $1 and $2?

In the replacement string, $1 refers to the first captured group, $2 to the second, and so on. $& refers to the entire match. These let you rearrange or reformat matched content. For example, replacing (\w+)@(\w+) with '$1 at $2' transforms 'user@domain' to 'user at domain'.

What does the 'g' flag do in regex replace?

The 'g' (global) flag replaces ALL matches in the text. Without it, only the first match is replaced. Always use 'g' when you want to replace every occurrence, not just the first one.

Can I use regex groups in the replacement string?

Yes, use $1, $2, $3, etc. to reference captured groups from your pattern. $& inserts the entire match. $` inserts text before the match. $' inserts text after the match. These special tokens enable powerful text transformations.

Is this regex replacer free?

Yes, completely free with no signup required. Replace unlimited patterns in any text. All processing happens in your browser for complete privacy.

Is my data secure?

Yes, all processing happens locally in your browser using JavaScript. Your text and patterns never leave your device, are never sent to servers, and are never stored anywhere.

How do I replace special characters?

Escape special regex characters in the pattern with backslash: \. \* \+ \? etc. In the replacement string, use $$ to insert a literal dollar sign. Backslashes in the replacement don't need double-escaping.

Can I do case-insensitive replacement?

Yes, add the 'i' flag along with 'g' (use 'gi' in the flags field). This makes the pattern match regardless of case, so 'hello', 'Hello', and 'HELLO' would all be matched and replaced.

What's the difference between Regex Tester and Regex Replacer?

The Regex Tester finds and displays matches with positions and groups. The Regex Replacer actually transforms the text by substituting matches with your replacement string. Use Tester to develop patterns, Replacer to transform text.

How do I remove matched text?

Leave the replacement field empty. The matched text will be replaced with nothing, effectively deleting it. This is useful for stripping unwanted patterns from text.

Can I use lookahead/lookbehind in replacements?

Yes, lookahead (?=...) and lookbehind (?<=...) assertions work in the pattern. They match positions without consuming characters, so the looked-at text remains unchanged. Only the actual match (not the assertion) is replaced.

How do I replace newlines or tabs?

Use \n in the pattern to match newlines and \t for tabs. In the replacement string, you can use literal newlines or the escape sequences depending on your needs. The 's' flag makes dot match newlines too.

Regex Replacer Tool

Why Use Our Regex Replacer?

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Complete Regex Replacement Guide