Regex101 Alternative — Online Regex Tester

Q: Does it support the same regex flavors as regex101?

This tester uses the JavaScript RegExp engine, which covers the ECMAScript regex flavor. That's the right choice if you're writing frontend JavaScript, Node.js, or any JS-based environment. JavaScript regex supports most of the features developers use daily: character classes, quantifiers, lookahead/lookbehind, named capture groups ( (?<name>...) ), and Unicode property escapes ( \p{Letter} with the u flag). It does not support PCRE-only features like recursive patterns or possessive quantifiers. If you need Python re semantics specifically, use the Python Regex Tester variant.

Test regular expressions in real time with live match highlighting, capture group display, and multi-string testing. No account required.

Why Use This Regex Tester

Real-time regex testing means you see matches update as you type — no submit button, no page reload. This tester highlights every match inline in your test string, breaks out named and numbered capture groups, and lets you run the same pattern against multiple test strings at once. It's the fastest way to iterate on a pattern until it does exactly what you want.

Live match highlighting: Matches and capture groups update on every keystroke
Capture group display: Numbered and named groups shown separately with their matched values
Multi-string testing: Paste several test strings and see which ones match
Flag controls: Toggle g, i, m, s flags with one click
No account needed: Start testing immediately with no login or sign-up

Test Regex →

Choose the Right Variant

This page: General-purpose JavaScript regex tester with live highlighting and capture groups
JavaScript Regex Tester: JS-specific patterns with String.match and String.replace output
Python Regex Tester: Python re module semantics including named groups and verbose mode
Email Regex Tester: Pre-loaded patterns for validating email address formats

Key Features

JavaScript regex engine: Uses the browser's native RegExp — identical results to what your JS code will produce at runtime
Named capture groups: Patterns like (?<year>\d{4}) display with their group names alongside matched text
Match count and index: Each match shows its start/end character index in the source string
Replacement preview: Enter a replacement string to preview String.replace output before using it in code
Error feedback: Invalid regex syntax is flagged immediately with a description of the error
No data sent anywhere: Pattern and test strings stay in the browser — safe for testing against real user data samples

Privacy and Data Handling

All processing runs in your browser. No data is sent to any server. Your regex patterns and test strings — including any real data you paste for testing — never leave your device.

Frequently Asked Questions

Does it support the same regex flavors as regex101?

This tester uses the JavaScript RegExp engine, which covers the ECMAScript regex flavor. That's the right choice if you're writing frontend JavaScript, Node.js, or any JS-based environment. JavaScript regex supports most of the features developers use daily: character classes, quantifiers, lookahead/lookbehind, named capture groups ((?<name>...)), and Unicode property escapes (\p{Letter} with the u flag). It does not support PCRE-only features like recursive patterns or possessive quantifiers. If you need Python re semantics specifically, use the Python Regex Tester variant.

Can I save and share patterns?

You can share a pattern by copying the page URL — the tester encodes your current pattern and flags into the URL hash, so bookmarking or sharing the URL restores the exact state. There's no account or database involved; the state lives entirely in the URL. For long-term storage of patterns you reuse, most developers keep them as comments or constants in their codebase alongside a link to the tester URL for quick re-testing.

Does it show capture groups?

Yes. Every match is expanded to show all capture groups — both numbered ($1, $2) and named ((?<groupName>...)). For each match, you can see the full match, then each group's matched substring alongside its group index or name. Non-participating groups (optional groups that didn't match) are shown as undefined so you can distinguish "group didn't match" from "group matched an empty string."