Flags
Classes
Quantity
Anchors
Groups
How to use
What it is and what it's for
Test regular expressions (regex) in real time, 100% in your browser. Type a pattern above and the text to analyze below: matches are highlighted instantly and listed one by one with their position and groups. Buttons to insert the common symbols, a library of ready-made patterns, a button to generate an example that matches, a pattern explanation panel and a Replace mode.
Flags: one by one
The Flags buttons change how the pattern is applied (hover over each for its explanation). g (global) is always active: ALL matches are shown.
• i case-insensitive.
• m multiline (^/$ per line).
• s the . also matches the newline.
• u Unicode (\p
Generate an example that matches
The Generate example button automatically creates a text that satisfies your pattern and adds it to the «Test text», where you will see it highlighted. It is the quick way to check that the regex matches what you think. Each generated text is self-verified against your regex before being shown; if the pattern is very complex (or impossible) it may fail to find one and will warn you.
Library and cheat sheet
Library: pick a ready-made pattern (email, DNI/NIE, date, IPv4, UUID…) and it loads the pattern and a sample text so you can see it in action. Cheat sheet: the buttons below the pattern insert the symbol at the cursor position (classes \d \w \s, quantities * + ?
Matches and groups
Each match shows its text, its position (character where it starts, 0-based) and all its capture groups, numbered (1, 2…) and named. A group (...) captures what matches inside; (?<year>...) names it; (?:...) groups without capturing. With Copy/Export you take away all matches (one per line or CSV) for data extraction.
Explanation panel
The explanation panel breaks your pattern down part by part in plain language: what each class, quantifier, group or anchor does. Ideal for understanding someone else's regex or reviewing your own before taking it to code.
Replace mode
Switch to the Replace tab and type the replacement string: you will see the result live. Reference groups with $1, $2… (numbered), $<name> (named), $& (the whole match) and $$ (a literal $). E.g.: pattern (\d
Syntax cheat sheet
• Classes: \d digit, \w letter/number/_, \s space; uppercase means the opposite. . any character.
• Sets: [aeiou], range [a-z], negated [^0-9].
• Quantity: * 0+, + 1+, ? 0/1,
