regex tester
Test, validate, and extract regex matches instantly. Paste your pattern and text to see all matches, groups, and indexes in your browser.
What regex tester Does
It takes a regular expression pattern and a block of test text, executes the pattern against the text, and returns a structured report listing every match, its character index, and any captured groups. It also validates pattern syntax, formats or minifies patterns, and extracts all matches as a plain list.
Who Uses This Tool
regex tester is built for Web developers, backend engineers, data engineers, QA testers, security analysts, technical writers working with pattern-based parsing. Whether you are processing data as part of an automated pipeline or need a quick one-off conversion in your browser, the tool requires no installation and no account — paste your input and get your result in seconds.
Primary Use Case
Verifying that a regex pattern correctly matches all intended strings — and nothing unintended — before embedding it in production code.
The Problem It Solves
Writing regex blind in a code editor means running the full application to see whether a pattern matched — a slow cycle that turns a one-minute task into twenty. Developers frequently ship patterns with missing flags, off-by-one group indexes, or unintended matches on edge-case strings because there was no fast feedback loop. Regex Tester removes that cycle: pattern, test text, result — in one step, with exact match positions and group values visible immediately, before any code is touched.
Example
/(\w+)@(\w+\.\w+)/g Contact us at hello@example.com or support@test.org
REGEX TEST RESULT ════════════════════════════ Pattern : /(\w+)@(\w+\.\w+)/g Matches : 2 [1] hello@example.com Index: 15 Groups: $1: hello $2: example.com [2] support@test.org Index: 36 Groups: $1: support $2: test.org
When to Use This Tool
Use this tool when building, debugging, or validating regular expressions for JavaScript, form validation, parsing, scraping, filtering, or text processing. It is especially useful for developers testing complex regex patterns with flags and capture groups.
What to Do With the Output
They copy the confirmed pattern directly into source code, use the extracted match list to spot-check real data samples, or reference the group indexes to map capture variables in replace or split operations.
Common Mistakes to Avoid
Forgetting the g flag causes the tester to return only the first match — the tool forces global matching internally for the report, but the copied pattern won't behave that way in code without it. Leaving out the test text entirely triggers an error; the pattern must be on line one and test text must follow on a new line. Using intentional whitespace inside a verbose-style pattern and then running Minify will silently destroy it. JavaScript regex does not support lookbehind in older environments, so patterns using (?<=...) may fail at runtime even if the tester accepts them. The match report displays positional groups ($1, $2) only — named capture group labels are not shown separately.
How It Works
The tool parses a regex pattern and flags, compiles them using the JavaScript RegExp engine, and executes the expression against the provided text input. Match results, capture groups, indexes, validation status, and extracted matches are then generated dynamically in real time.
Also Known As
regex tester is also commonly referred to as regular expression tester, regexp tester, regex checker, regex pattern tester, regex match tester, test regex online, regex validator online, regex debugger, regex sandbox. All of these terms describe the same conversion — no matter what you call it, this tool handles it.