Test Regular Expressions with Live Feedback
Write expressions, test against sample text, view matches, and export results as JSON or CSV for your automation scripts.
Cheat-sheet
Basics
. any, \\d digit, \\w word, \\s whitespace
Quantifiers
+ one+, * zero+, ? optional, {m,n}
Anchors
^ start, $ end, \\b word boundary
Groups
( ), (?: ), (?<name> )
Lookarounds
(?= ), (?! ), (?<= ), (?<! )
Enter a pattern (e.g., \\d+).
Overview
Regular expressions are powerful but unforgiving. Our tester provides instant feedback, capture breakdowns, and replacement previews so you can build patterns confidently.
Because everything runs locally, you can debug logs, customer data, or proprietary templates without risk.
Key features
Live highlighting
Matches appear instantly in the text pane with unique colours for each capture group.
Replacement engine
Preview replacements using $1 syntax and export transformed text without leaving the tool.
Flags & presets
Toggle common flags (global, multiline, case-insensitive) and start from sample patterns for URLs, emails, and more.
Structured exports
Copy match results as JSON, CSV, or newline-separated lists for further processing.
How it works
- 1
Enter your pattern
Type or paste your regex in the pattern field and enable relevant flags.
- 2
Provide sample text
Paste the data you want to test or use built-in samples to verify the pattern quickly.
- 3
Review matches
Check highlighted matches, capture groups, and counts to confirm the regex behaves as expected.
- 4
Export results
Copy matches or replacements to use in scripts, ETL pipelines, or quick clean-up tasks.
Use cases
Data cleaning
Extract email addresses, order IDs, or error codes from log files for further analysis.
Validation rules
Test form validation patterns before implementing them in production code.
Search-and-replace migrations
Preview large-scale replacements before running them against repositories or CMS exports.
Examples & tips
Normalize phone numbers
Use capture groups to format international phone numbers consistently.
Extract Markdown links
Match [text](url) patterns and export results to audit outbound linking.
Clean analytics exports
Strip query parameters or hash fragments from URLs before loading them into dashboards.
Pro tips
- Review capture groups carefully—unexpected matches usually mean you need non-greedy quantifiers.
- Pair with the Data Converter to reshape matched data into CSV or JSON outputs.
Frequently asked questions
- Which regex flavour is supported?
- The tester uses JavaScript regular expressions. Patterns compatible with ECMAScript will work here.
- Can I save patterns?
- Use browser bookmarks or copy the pattern JSON export for future reference.
- Is there a dark mode?
- Yes, the tester respects the site theme, making late-night debugging easier.
- Does the tool store my data?
- No, everything stays in your session. Clear the input fields when finished.
Resources & internal links
What's next?
Validate your expression above, export the matches, and drop them into your next ETL job or quick script with confidence.