Probador de Regex

Prueba una expresión regular contra tu texto mientras escribes. Las coincidencias se resaltan, los grupos de captura se listan, y una biblioteca de presets carga un patrón común con un clic. Nada se sube.

Sintaxis de regex estándar de JavaScript. Sin slashes, sin flags alrededor.

Flags
Presets
0 coincidencias

Coincidencias

  1. Las coincidencias aparecerán aquí mientras escribes.

El motor RegExp de JavaScript se ejecuta por completo en tu navegador. El patrón, texto de prueba y coincidencias nunca salen de esta página — no hay llamadas de red.

About this tool

Regex Tester is a live playground for ECMAScript regular expressions. You write a pattern and one or more test strings, and the tool highlights every match in the input, lists the captured groups, and reports the index of each match. Flags (g, i, m, s, u, y) are selectable as checkboxes. The pattern is parsed as it is typed, so a syntax error shows up immediately with the same error the browser would produce. The tester also offers a short cheatsheet of the most common character classes and quantifiers, accessible from the help button.

When to use it

  • Iterating on a regex pattern against real input data without opening a code editor
  • Debugging a pattern from a stack-overflow answer to see exactly what it matches
  • Verifying that a pattern handles edge cases (empty string, Unicode, newlines) before shipping it
  • Teaching a colleague the basics of regular expressions with a live, side-by-side view

When not to use it

  • You need a regex flavour other than ECMAScript (PCRE, Python, RE2) — different engines have different extensions. This tool follows JavaScript's RegExp exactly
  • You need to run a regex over a large file — paste representative samples, the tester is for development, not bulk processing
  • You need named-group extraction with replacement — the tester matches, it does not substitute

Frequently asked questions

Which regex flavour does it use?

ECMAScript (JavaScript), with full support for Unicode property escapes, lookbehind, and named groups. The behaviour matches what you will see in Node.js and in modern browsers. It is not compatible with PCRE, POSIX, or Python's re module — those have different extensions.

How do I match across lines?

Turn on the `s` flag (dotAll). With `s`, `.` matches any character including newlines. Without it, `.` stops at the end of each line.

Why does my pattern behave differently here than in my code?

Most often it is a missing flag, or a difference in string handling (the tester treats input as a single string, while your code may be reading line-by-line). Check the flags, and try the same input as a single string.

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