Regex Playground

LOCAL · Browser-Only

Build, test, and debug regular expressions with real-time match highlighting

Regex Pattern

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What is Regex Playground?

Free online regex playground that goes beyond basic testing.

Build, test, and debug regular expressions with real-time match highlighting, capture group inspection, and a find-and-replace mode for regex substitution. Browse a library of common regex patterns (email, URL, phone, IP address, dates, hex colors, HTML tags, and slugs) to jumpstart your work and learn regex by example. Toggle regex flags interactively, see alternating match colors for clarity, and share your regex via URL. All processing runs locally in your browser, so your data never leaves your device. No signup required.

How to Use Regex Playground

1Enter a regex pattern in the pattern field, or choose one from the Common Patterns library
2Select the flags you need (global, case-insensitive, multiline, dotAll, unicode)
3Type or paste your test string to see matches highlighted in real time
4Inspect capture groups below the highlighted output for detailed group information
5Switch to Find & Replace mode to test substitution patterns using $1, $2, or $&

Frequently Asked Questions

What makes this different from a basic regex tester?

The Regex Playground adds a common patterns library with ready-to-use expressions, a built-in find-and-replace mode, detailed capture group inspection (including named groups), alternating match colors for visual clarity, and full URL sharing. It is designed for both learning and production-level regex work.

What regex flags are supported?

Five flags are supported: g (global - find all matches), i (case-insensitive), m (multiline - ^ and $ match line boundaries), s (dotAll - dot matches newlines), and u (Unicode - enable full Unicode matching). Toggle them individually with the flag buttons.

How does find and replace work?

Switch to Find & Replace mode, enter your regex pattern and flags, type your replacement string (using $1, $2 for captured groups or $& for the full match), and the replaced output appears in real time. You can copy the result with one click.

Is my data safe?

Yes. All regex matching and replacement runs entirely in your browser using JavaScript's built-in RegExp engine. No data is sent to any server.

Where can I find a ready-made pattern for email or URLs?

Open the Common Patterns library and pick from prebuilt expressions for email, URL, phone number, IP address, dates, hex colors, HTML tags, and slugs. Selecting one loads it into the editor so you can test it against your own text or adapt it.

Can I share a regex with a teammate?

Yes. The current pattern, flags, and test string are encoded in the page URL. Copy the URL and send it, and your teammate opens the playground with the exact same setup ready to run.

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Keep reading: Cron Expression Cheat Sheet and regex syntax reference. Doing this in code instead? See the JSON and data endpoints.