What regex flavors does it support?

Formly's regex tester uses JavaScript's native RegExp engine, which supports standard regex syntax compatible with most modern languages.

How do I test a regex?

Type or paste your regular expression in the Pattern field, add any flags (g for global, i for case-insensitive, m for multiline), then paste your test string. Matches are highlighted in real time.

Can I test regex replacements?

Yes — enable Replace mode and enter a replacement string to preview the result of regex substitution before using it in code.

Is there a library of common patterns?

Yes — the Quick Patterns library includes ready-to-use patterns for email addresses, URLs, phone numbers, IP addresses, dates, credit cards, and more.

All Tools

🔍

Regex Tester

Free to Use

Test regular expressions live. Highlight matches, inspect groups, use replace mode, and pick from a library of common patterns.

Pattern

//g

g — globali — case insensitivem — multilines — dot all

Quick Patterns

Test String

Frequently Asked Questions

Is this regex tester free?›

Yes, entirely free with no account needed. You can test as many patterns as you like without any limits.

Which regex flavour does it support?›

It uses the JavaScript (ECMAScript) regex engine built into your browser. This supports most common features — character classes, quantifiers, lookaheads, named groups — but not PCRE-only syntax like \K or atomic groups.

How reliable are the match results?›

Results are produced by the same JavaScript RegExp engine your production code runs on, so what you see here is exactly what you will get in a JS/TS application. The highlight and group inspector update in real time as you type.

What are common use cases?›

Validating email or phone formats, extracting URLs from text, writing search-and-replace scripts, testing log-parsing patterns, and learning regex syntax interactively with the built-in quick-pattern library.

Is my text data private?›

Yes. Everything runs in your browser. Your pattern and test strings are never sent to any server.

What Is Regex Tester & Debugger?

A regex tester lets you write, test, and debug regular expressions in real time against test strings. Formly's free regex tester highlights matches, groups, and captured subgroups inline, shows the full match object with group names and indices, and provides a regex explanation in plain English for each pattern. Supports JavaScript regex flavor with all standard flags (g, i, m, s, u).

Why Formly's Regex Tester & Debugger Is the Best Free Option

✓Live highlighting — matches and capture groups highlighted as you type the regex.
✓Plain English explanation — converts complex patterns to human-readable descriptions.
✓Named groups support — displays captured group names and their matched values.
✓Multiple flag support: global, case-insensitive, multiline, dotAll, unicode.
✓Test multiple strings — run your regex against multiple inputs simultaneously.
✓Free with no account required.

Free Alternative to Regex101, Regexr

→Regex101: Regex101 is excellent but adds complexity. Formly is focused and faster for quick tests.

→Regexr: Similar capability, Formly has cleaner UI and AI-powered plain English explanations.

Who Uses Regex Tester & Debugger?

Developers

Test and debug validation patterns (email, phone, URL) before adding to production code.

Data analysts

Build patterns for extracting structured data from text logs and CSV files.

QA engineers

Verify test case patterns match expected input formats.

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Looking for a detailed guide? Read our in-depth tutorial on using Regex Tester & Debugger for professional results.

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