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Regex tester — build and test a regular expression

FreeNever uploaded

This one runs in your browser. Nothing you type leaves this page, and it costs nothing. The output updates as you type.

Before and after

A log you would otherwise read by eye, turned into a table of what the pattern caught.

Pattern
(?<method>GET|POST|PUT|DELETE) (?<path>/\S*) (?<status>\d{3}) (?<ms>\d+)ms
Matches
linemethodpathstatusms
1GET/api/orders?id=419220031
2POST/api/login40112

What this tool does

This tool runs a regular expression over text you paste and lists every match: where it starts (line and column), the text it matched, and what each capture group — named or numbered — caught. Beside the table it reads the pattern back to you token by token in plain English, which is the quickest way to see why a pattern matches too much or nothing at all. It uses JavaScript's own regex engine with the flags you choose (i, m, s, u, y; g is implied, because every match is listed). Everything runs in your browser: the text you paste is never uploaded, and nothing you type leaves this page.

What happens to your file

Your file never leaves your device. This page opens it, changes it and saves the result in your browser; nothing is uploaded, so there is no copy on our servers to delete.

No AI provider sees it either. The page sends us one count that a run happened — no file, no name, no size. Details on the privacy page.

Questions

Which regex flavour is this?

JavaScript's, as your browser runs it — the same engine a regex in a web page or a Node.js script uses. Named groups, lookbehind and Unicode property escapes work where your browser supports them. PCRE-only syntax such as possessive quantifiers is reported as an error rather than silently treated as something else.

Is my text uploaded anywhere?

No. The pattern and the text are run by code on this page, in your browser. Nothing is sent to our servers or to anyone else, so it is safe to paste a log with internal paths in it.

Why does my pattern match nothing?

Read the explanation beside the result: it spells out what each token asks for, which usually shows the problem — an unescaped dot, a missing m flag for ^ and $ on each line, or a greedy .* swallowing the rest of the line. A pattern that does not compile is reported as an error rather than as an empty table.

Can a pattern hang the page?

A badly backtracking pattern can be slow on long text. The search stops after two seconds and says so rather than running on; one pathological match can still take a moment, because nothing inside a browser tab can interrupt it.

Is it free?

Yes, with no account and no daily limit. It runs on your own device, so it costs us nothing to offer.

Text & data

On ExploreMyData, our sister site