Regex → Plain English Translator
Paste a regular expression and see exactly what it does — in plain English, not regex syntax. Get a token-by-token breakdown, a visual pattern map, a live test against your own sample text, and a catastrophic-backtracking warning if the pattern looks risky. Nothing you paste ever leaves your browser.
What this tool does
Paste any JavaScript-flavored regex pattern and this tool explains it piece by piece — what each group, class, quantifier, and anchor actually matches — then shows a visual pattern map and lets you test it live against your own sample text with matches highlighted inline.
Free features
- Plain-English breakdown of every token: character classes, quantifiers, anchors, groups, alternation, backreferences, lookaheads/lookbehinds
- Visual pattern map (inline SVG, no external diagram tool or signup required)
- Live match highlighting against your own sample text, with capture groups broken out by name or index
- Catastrophic-backtracking (ReDoS) warning — flags risky nested-quantifier and alternation shapes most free tools don’t check for at all
- Starter pattern library (email, URL, IPv4, hex color, date, US phone, slug) to learn from or drop straight in
- Friendly error messages instead of raw JavaScript syntax errors
- Copy the pattern or the full breakdown as plain text
- Your last pattern, flags, and sample text are remembered automatically between visits — no account needed
- No row, character, or usage caps of any kind
What other regex explainers charge for (and we don’t)
Most free regex explainers online cap you to short patterns, hide the visual diagram behind a signup wall, or limit how many times you can run a pattern per day. This tool has none of that — every feature above is free, permanently, with no account and no limits.
Already have a pattern you want to test against real data?
This tool is built for understanding a pattern. If you want full match-by-match control over your own text — different flags, bulk test strings, multiple matches inspected side by side — use the Regex Tester instead. Both tools share the same safety engine under the hood, so behavior is identical between them.
FAQ
Is this a real regex engine, or an approximation?
The live match test uses your browser’s own JavaScript regex engine — the real thing, not a simulation. The plain-English breakdown and pattern map come from a separate parser built for this tool; on rare exotic syntax it doesn’t fully model, the live test above it is still 100% accurate.
Does this work for Python, PCRE, or other regex flavors?
This tool explains JavaScript-flavored regex specifically. Most common syntax (classes, quantifiers, groups, lookaround) is shared across flavors, but named-group syntax, lookbehind support, and a few edge cases vary by engine — the tool flags common portability gotchas where relevant.
Is my pattern or sample text uploaded anywhere?
No. Everything — parsing, matching, and the diagram — runs locally in your browser. Nothing is sent to a server.
Why does it say my pattern “looks risky”?
A small number of regex shapes (like a repeated group that can itself match a variable number of characters) can cause a browser tab to freeze on certain input — this is called catastrophic backtracking. This tool checks for those shapes and, if it finds one, runs the live test against a short snippet instead of your full sample text, so your tab stays responsive either way.