SoftnagFree

Regex Tester & Matcher

PopularDeveloper Tools

Test, debug, and validate Regular Expressions in real time with live color-coded match highlighting, capture groups, and regex pattern library.

100% In-Browser Privacy
Zero Server Uploads
Active Flags:

Captured Matches (2)

support@softnag.qzz.ioIndex: 20
Group 1: support
Group 2: softnag.qzz.io
aakash@softnag.qzz.ioIndex: 76
Group 1: aakash
Group 2: softnag.qzz.io

Who Is Regex Tester & Matcher Built For?

Software developers debugging regex patterns for input validation and string parsing
DevOps engineers authoring log filtering rules for Grafana, Datadog, and ELK stacks
Data analysts extracting structured tokens and email addresses from raw text logs

Key Benefits & Core Capabilities

Real-Time Match Highlighting

Highlights regex matches, capture groups, and named groups instantly as you type.

All Standard Regex Flags

Toggle Global (g), Case-Insensitive (i), Multiline (m), DotAll (s), and Unicode (u) flags.

Capture Group Breakdown Table

Inspect numbered capture groups ($1, $2) and named groups in a clear structured table.

Common Pattern Cheatsheet

Built-in library of verified regex templates for emails, URLs, IP addresses, dates, and phone numbers.

Step-by-Step Guide: How to Use Regex Tester & Matcher

  1. 1
    Enter PatternType your regular expression pattern.
  2. 2
    Toggle FlagsEnable global (g), case-insensitive (i), or multiline (m) flags.
  3. 3
    Review MatchesInspect match indexes and captured sub-groups in real-time.

How It Works & Technical Architecture

The Regex Tester utilizes the browser’s native JavaScript RegExp engine enhanced with safety limits to detect catastrophic backtracking risks (ReDoS).

As you type your pattern, it compiles the regular expression, tests it against the sample text string, and records all match intervals and capture group indices.

The text is rendered with layered color-coded highlights, making it effortless to understand complex group matches.

Practical Use Cases & Applications

Form Input Validation

Author and test regex rules for validating email addresses, passwords, phone numbers, and postal codes.

Log File Token Extraction

Craft regex patterns to extract IP addresses, HTTP status codes, and user agents from server logs.

String Search & Replace Testing

Test regex substitution patterns before executing batch refactoring in IDEs.

Data Cleaning & Scraping

Extract specific numerical identifiers, prices, and SKUs from unstructured HTML text.

Supported Formats & Input Options

JavaScript RegExpPCRE Compatible PatternsSample Text Data

Frequently Asked Questions

Which regex dialect does this tool use?

The tool uses the modern ECMAScript/JavaScript RegExp engine, which is broadly compatible with PCRE, Python, and Go regular expressions.

How do I see captured groups ($1, $2)?

Softnag displays a dedicated Capture Groups inspector table listing all matched subgroups with their exact character indices.

Does the tool support named capture groups (?<name>...)?

Yes. Named capture groups are fully supported and displayed with their assigned property names.

Is my test text uploaded to any server?

No. All regex matching and testing execute strictly within your local browser sandbox.

How do I prevent catastrophic backtracking (ReDoS)?

Softnag incorporates execution time guards that safely terminate complex nested quantifier loops before they can freeze your browser.

Which regex dialect is used?

It uses the native JavaScript RegExp engine conforming to the ECMAScript standard.