Developer tools
Regex Tester

Regex tester

Write a pattern and watch matches highlight as you type. Inspect every match and capture group, try a replacement, and keep test cases that must — or must not — match, so a regex that works today still works after your next edit.

Open Regex Tester — free Get the Windows app

Free in your browser — no sign-up. Install from the Microsoft Store to use it offline on Windows 10 and 11.

How to use it

Open the Regex Tester, type a pattern and set flags such as g, i or m.
Paste your test text. Matches highlight live, and Match details lists every group.
Add test cases or try Replace all, then copy the finished pattern.

Example

Pattern and text

Pattern  (\d{4})-(\d{2})-(\d{2})   flags: g

Text     Released 2025-01-01, patched 2025-03-15.

Matches

Match 1  2025-01-01   groups: 2025 · 01 · 01
Match 2  2025-03-15   groups: 2025 · 03 · 15

Features

Live highlighting of every match as you type.
Match details — each full match and its capture groups.
Replace — preview a replacement across all matches.
Test cases — list inputs that should and shouldn’t match, and run them in one click.
Pattern library — ready-made patterns for email, IPv4, UUID, semver, hex colors, dates, phone numbers, HTML tags, JWTs and more.
AI assist — explain a pattern, generate one from a description, or find edge cases, with AI credits.

Frequently asked questions

Which regex flavor does this use?

JavaScript (ECMAScript) — the engine in browsers and Node.js. Most syntax is shared with PCRE, Python and .NET, but some features, such as lookbehind and named-group syntax, differ slightly between engines.

Why does my regex only find the first match?

Without the g (global) flag, JavaScript stops after the first match. Turn on g to find them all.

Is the regex tester free?

Yes. Testing, highlighting, replace, test cases and the pattern library are free. Only the AI features use credits.

One workspace for all of it

Regex Tester is one of 18 developer tools in CodeForge — alongside a JSON formatter, JWT decoder, regex tester, UUID and hash generators, and more. Press Ctrl+K to jump to any of them.