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CalcivoTools

Regex Tester : Live JavaScript Regular Expression Matcher

The Calcivo Regex Tester evaluates regular expressions in real time using the browser-native JavaScript RegExp engine. It highlights matching text patterns, lists capture groups, and displays syntax errors without transmitting text to third-party APIs.

Interactive Calculator

100% Client-Side Engine
//gi
105 chars
Match Highlight Preview2 matches found
Contact our engineering team at support@calcivo.site or dev.team+lead@example.org for technical feedback.
Detailed Match Results
Match #1 (index: 32)20 chars
support@calcivo.site
Group #1: support
Group #2: calcivo.site
Match #2 (index: 56)25 chars
dev.team+lead@example.org
Group #1: dev.team+lead
Group #2: example.org

Engine: Regex execution uses the browser's JavaScript ECMAScript RegExp engine. Extremely complex patterns or nested quantifiers may be computationally expensive.

Client-Side In-Browser Evaluation

Step-by-Step Examples

Extracting Email Addresses

Matching user email addresses with username and domain groups.

Inputs: Pattern: ([a-zA-Z0-9._%+-]+)@([a-zA-Z0-9.-]+\.[a-zA-Z]{2,})
Result: Highlights emails and extracts Group 1 (user) and Group 2 (domain).

Accurately isolates local parts from domain parts across arbitrary text.

How to Use This Tool

  1. Input your regular expression pattern between the forward slashes.
  2. Toggle flags such as Global (g), Case-Insensitive (i), Multiline (m), or DotAll (s).
  3. Type or paste your test text into the test area.
  4. Inspect real-time color highlights and detailed capture group extractions.

Frequently Asked Questions

Calcivo utilizes your web browser’s native ECMAScript RegExp engine (V8 on Chrome/Edge, JavaScriptCore on Safari, SpiderMonkey on Firefox). Syntax unique to PCRE or Python may behave differently.

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