Categories

← View All Tools

Regex Replace Previewer

Preview regex replacements in real-time with detailed diff highlights and statistics

Features:

  • Real-time preview of text replacements
  • Support for capture groups ($1, $2, ${name})
  • Special patterns: $& (full match), $` (prefix), $' (suffix), $$ (literal $)
  • Diff highlights showing changes
  • Detailed statistics on replacements

Example Usage:
Pattern: \b(\d{4})-(\d{2})-(\d{2})\b
Replacement: $2/$3/$1
Input: "Dates: 2024-01-15 and 2024-02-20"
Output: "Dates: 01/15/2024 and 02/20/2024"

Enter the regular expression pattern to search for

Use $1, $2, ${name} for capture groups. Special: $& (match), $` (prefix), $' (suffix), $$ (literal $)

Regex flags: g (global), i (case-insensitive), m (multiline), etc.

Choose how to display the replacement preview

Key Facts

Category
Development
Input Types
textarea, text, select
Output Type
json
Sample Coverage
4
API Ready
Yes

Overview

The Regex Replace Previewer is a development tool that lets you test regular expression substitutions in real-time. It provides immediate visual feedback with diff highlights and detailed statistics, ensuring your patterns work as expected before deployment.

When to Use

  • •When developing or debugging regex patterns for text processing tasks.
  • •To visually confirm how replacements will alter your text with highlighted differences.
  • •For analyzing the impact of regex operations through match and replacement counts.

How It Works

  • •Input your original text into the designated textarea.
  • •Define the regex pattern and replacement template, utilizing capture groups like $1 or special patterns such as $&.
  • •Set optional regex flags (e.g., g for global) and select a preview mode (side-by-side, inline-diff, or result-only).
  • •The tool instantly displays the modified text with changes highlighted and provides statistics on the replacements made.

Use Cases

Reformatting date strings in log files to a different standard.
Cleaning and standardizing phone numbers or email addresses in datasets.
Extracting specific data patterns from unstructured text for analysis.

Examples

1. Convert Date Formats

Software Developer
Background
Working with server logs that contain dates in ISO format (YYYY-MM-DD).
Problem
Need to change dates to US format (MM/DD/YYYY) for a compliance report.
How to Use
Enter the log text, set pattern to `\b(\d{4})-(\d{2})-(\d{2})\b`, and replacement to `$2/$3/$1`.
Outcome
Dates are converted, and the diff view shows all changes clearly.

2. Standardize Phone Numbers

Background
Has a CSV file with phone numbers in various formats like (123) 456-7890 and 123-456-7890.
Problem
Inconsistent formats prevent accurate data merging and analysis.
How to Use
Use a regex pattern to match different formats, e.g., `(\d{3})[^\d]*(\d{3})[^\d]*(\d{4})`, and replacement `$1-$2-$3`.
Outcome
All phone numbers are standardized to 123-456-7890 format, with statistics showing the number of replacements.

Try with Samples

text, regex
Regex Replace Samples
Collection of common and useful regex replacement patterns for text transformation and data cleaning
title token regex,replace
regex
Regex Pattern Alternatives
Multiple ways to write the same regex pattern with different trade-offs in readability, performance, and accuracy
title token regex
regex
Regex Named Capture Groups
Collection of regex patterns using named capture groups for extracting structured data from text. Named groups make patterns more readable and maintainable by assigning meaningful names to captured portions.
title token regex
regex
Common Regex Patterns
Commonly used regular expression patterns for validation and matching
title token regex
regex

Related Hubs

Text Tools
Explore 33 text tools for utility workflows and compare closely related utilities quickly.
Text Convert Tools
Explore 80 text tools for convert workflows and compare closely related utilities quickly.
Text Analyze Tools
Explore 12 text tools for analyze workflows and compare closely related utilities quickly.
Text Format Tools
Explore 9 text tools for format workflows and compare closely related utilities quickly.

FAQ

What regex flags can I use?

Common flags like g (global), i (case-insensitive), and m (multiline) are supported.

How do I use capture groups in replacements?

Use $1, $2, etc., to refer to captured groups in the replacement template.

What are the special replacement patterns?

Special patterns include $& for the full match, $` for the prefix, $' for the suffix, and $$ for a literal dollar sign.

Can I see a diff of the changes?

Yes, the tool highlights additions, deletions, and modifications in the preview.

Does it provide statistics on replacements?

Yes, it shows the number of matches found and replacements made.

API Documentation

Request Endpoint

POST /en/api/tools/regex-replace-previewer

Request Parameters

Parameter Name Type Required Description
textInput textarea Yes -
pattern text Yes Enter the regular expression pattern to search for
replacement text Yes Use $1, $2, ${name} for capture groups. Special: $& (match), $` (prefix), $' (suffix), $$ (literal $)
flags text No Regex flags: g (global), i (case-insensitive), m (multiline), etc.
previewMode select No Choose how to display the replacement preview

Response Format

{
  "key": {...},
  "metadata": {
    "key": "value"
  },
  "error": "Error message (optional)",
  "message": "Notification message (optional)"
}
JSON Data: JSON Data

AI MCP Documentation

Add this tool to your MCP server configuration: 

{
  "mcpServers": {
    "elysiatools-regex-replace-previewer": {
      "name": "regex-replace-previewer",
      "description": "Preview regex replacements in real-time with detailed diff highlights and statistics",
      "baseUrl": "https://elysiatools.com/mcp/sse?toolId=regex-replace-previewer",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

You can chain multiple tools, e.g.: `https://elysiatools.com/mcp/sse?toolId=png-to-webp,jpg-to-webp,gif-to-webp`, max 20 tools.

If you encounter any issues, please contact us at [email protected]