Does this regex tester run in my browser or send data to a remote server?

Regex testing and string analysis run locally in your browser memory. Your regular expressions, test strings, and replacement results are processed exclusively client-side and never transmitted across the network.

Which regular expression flags are supported?

This tool supports standard JavaScript ECMAScript flags: g (Global), i (Ignore Case), m (Multiline), s (DotAll), u (Unicode), y (Sticky), and d (Indices where supported by the browser engine).

How are capturing groups and named groups displayed?

Each match provides a detailed breakdown of full matched text, character offset, line and column numbers, numbered capture groups ($1, $2), and named capture groups (? ).

What string diagnostics and Unicode statistics are calculated?

The string debugger provides real-time counts for UTF-16 code units, Unicode code points, UTF-8 byte sizes, line endings (LF, CRLF, CR), words, whitespace, digits, letters, and leading/trailing spacing.

What is catastrophic backtracking (ReDoS) and how should I avoid it?

Catastrophic backtracking happens when nested quantifiers or overlapping alternation branches cause exponential search steps on non-matching inputs. Using atomic groups, possessive-like logic, or bounded character classes helps prevent execution freezes.

JavaScript is Required

Zapixal is a client-side application. It requires JavaScript to process images securely in your browser without uploading them to a server. Please enable JavaScript to use this tool.

Client-Side

Regex Tester & String Debugger

Name: Zapixal - Regex Tester & String Debugger
Availability: InStock
Author: Zapixal

Test and debug regular expressions with live match highlighting, group inspection, Unicode diagnostics, and replacement previews locally in browser memory.

Developer Suite5 Tools

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