.* Regex Tester

Test and debug regular expressions live with real-time match highlighting. Supports flags, capture groups, and named groups. Free online regex tester — no signup needed.

/ /

g i m s

Test String

How to Use

Enter a pattern

Type your regular expression in the pattern field. Use the checkboxes to enable flags: g (global), i (ignore case), m (multiline), s (dotAll).

Add your test string

Paste or type the string you want to test in the Test String area. All matches are highlighted live as you type.

Inspect matches

See the total match count, each match with its position, and any capture groups. Copy the verified pattern to use in your project.

Frequently Asked Questions

What is a regular expression? +

A regular expression (regex) is a sequence of characters that defines a search pattern. They are used to match, find, or replace text in strings. For example, /\d+/ matches one or more digits.

What are regex flags and what do they do? +

Flags modify how a regex works. g (global) finds all matches, not just the first. i (ignore case) makes matching case-insensitive. m (multiline) makes ^ and $ match line boundaries. s (dotAll) makes . match newlines.

What are capture groups? +

Capture groups (...) let you extract specific parts of a match. For example, /(\d{4})-(\d{2})-(\d{2})/ matches a date and captures year, month, and day in separate groups. Named groups use (?<name>...) syntax.

Why does my regex not find all matches? +

Without the g (global) flag, the regex stops after the first match. Enable the g flag to find all occurrences. Also ensure you have not accidentally added anchors (^ or $) that restrict matching.

Is any data sent to a server? +

No. All regex processing runs entirely in your browser using JavaScript's built-in RegExp engine. Your pattern and test string never leave your device.

Guía: Probador de Expresiones Regulares

¿Qué es?

Las expresiones regulares (regex) describen patrones de texto para búsqueda, validación y transformación. Esenciales para validar formularios, analizar logs, y transformaciones en pipelines de datos.

Soportan: grupos de captura, lookaheads, lookbehinds, backreferences y flags g, i, m.

Cómo usar

Escribe el patrón en el campo superior (sin delimitadores).
Selecciona los flags: g (global), i (insensible), m (multilínea).
Ingresa el texto de prueba — las coincidencias se resaltan en tiempo real.
Revisa los grupos de captura en el panel de resultados.

Consejos

Usa (?:...) para grupos de no-captura cuando no necesites referenciarlos.
El flag g encuentra todas las coincidencias; sin él, solo la primera.
Para validar emails, usa una librería — las regex de email completas son extremadamente complejas.