⌘ K
javascript · pcre · two-way · local

Translate regex between JavaScript and PCRE

Convert named groups, inline flags, and other syntax differences in both directions. Warnings flag features that exist in only one flavour. Runs entirely in your browser.

JS ↔ PCRE Regex Converter
Direction
JavaScript regex
PCRE pattern
Conversions & warnings (3)
  • convert(?<name>) → (?P<name>) (PCRE Python-style form, also valid)
  • infoPCRE supports possessive quantifiers (*+, ++) and atomic groups (?>...) — not available in JS.
  • infoPCRE supports inline flags like (?i), (?m), (?s) — JS only accepts flags after the pattern.
Quick Start

How to convert between JavaScript and PCRE

Paste a regex in either flavour, pick the direction, and read the translated pattern alongside a list of conversions and warnings.

  1. 01

    Pick a direction

    Choose JS → PCRE or PCRE → JS. The shell switches placeholders and labels automatically.

    Patterns are parsed with the JavaScript RegExp constructor, so syntax errors surface immediately and engine quirks like Unicode property escapes (\p{L}) work when the u flag is on.

    patternECMAScriptliteralregex
    input · literaldirection · regex
    JS -> PCRE
    loaded · ECMAScriptPCRE · ready
  2. 02

    Paste pattern

    Drop your regex in. Named groups, inline flags, and \k references are all examined.

    Each flag character mirrors the ECMAScript literal: g enables iteration, i folds case, m anchors per line, s lets . match newlines, u unlocks proper Unicode, y is sticky, and d emits indices.

    flagsoptionsg · i · mlive
    config · optionsregex · flags
    (?<name>\w+)
    flags applied · liveECMA · live
  3. 03

    Read translation

    Conversions list the rewrites made — like (?<name>) becoming (?P<name>). Warnings call out features without a counterpart.

    Conversions translate flavour-specific constructs (lookarounds, named groups, character classes) — the converter flags anything that has no equivalent in the target engine.

    convertflavourPCRE · RE2diff
    run · outputdiff · converted
    (?P<name>\w+)
    matches · livediff · ready
  4. 04

    Copy result

    Grab the converted pattern with one click and drop it into your codebase.

    Copy writes via navigator.clipboard.writeText; downloads use a Blob and object URL, so nothing transits the network and the output is byte-identical to what you see on screen.

    copyexportclipboardblob
    export · exportedready · saved
    Copied
    ready to shipsuccess
Pro tips

Regex patterns that don't melt down

Use named groups

(?<year>\d{4}) reads better than $1 and survives reordering. Supported in ECMAScript 2018+.

Anchor strictly

Use ^/$ with the m flag when matching whole lines. Without anchors, partial matches sneak through.

Avoid catastrophic backtracking

Nested quantifiers like (a+)+ can explode. Run patterns through ReDoS Detector first.

Escape every literal

Backslash any meta character you want literally: \.\$\^\*\+\?\(\)\[\]\{\}\|\\.

Test edge cases

Empty string, single character, unicode, the maximum length you expect — write fixtures for each.

Patterns aren&rsquo;t parsers

Don’t parse HTML, JSON, or balanced parens with regex. Use a proper parser when the grammar is recursive.

Related toolsJs Python ConverterRegex Flavour DetectorJs Perl ConverterPosix Pcre ConverterRegex To PhpRegex Tester
Use Cases

When you need PCRE-aware translation

Bridging JavaScript regex with PHP, Apache, Nginx, and other PCRE engines.

Port to PHP

Reuse a JS regex inside preg_match without surprises. Compiles through the JavaScript RegExp constructor — engine quirks (Unicode property escapes, sticky matching, named groups) work when their flags are on. Error messages cite the exact position of any syntax issue.

ReDoS-safe

Apache rewrites

Lift a JS validator into mod_rewrite RewriteRule patterns. Pairs with the ReDoS detector to catch catastrophic backtracking before you deploy. A pattern that handles 1k-character input fine can become a denial-of-service vector on attacker-controlled 1M-character input.

ECMA-compliant

Nginx configs

Translate path patterns for nginx location blocks. Output exports as JavaScript, Python re, Java util.regex, .NET System.Text.RegularExpressions, PCRE, and POSIX — language quirks are highlighted on conversion so you don't ship a JS-only pattern to a Go service.

spec-grade

Document differences

Show colleagues which features changed between flavours. Capture groups (named or numbered) round-trip cleanly into replacement strings, JSON output, or CSV extraction without re-typing. Backreferences ($1, ${name}) preserve semantics across languages.

cross-engine

Audit named groups

Catch (?<name>) vs (?P<name>) mismatches in code review. Test against edge cases — empty input, single character, max length, multibyte boundaries — to catch off-by-one and zero-length match bugs before they reach production.

test-ready

Cross-language tests

Verify the same pattern behaves identically in JS and PHP. All matching runs client-side so secret patterns never leave the browser. Useful when the pattern itself is sensitive (PII regexes, internal data formats, security filters).

production-ready
FAQ

Frequently asked questions

Perl Compatible Regular Expressions — the regex engine used by PHP, Apache, Nginx, and many other tools.
Yes — PCRE-only forms like (?i) are stripped when going to JS, and warnings explain why.
PCRE uses (?P<name>) while JS uses (?<name>). The converter rewrites either form into the target syntax.
Warnings mean a feature has no direct counterpart — review the output before relying on it in production.
No. The conversion happens entirely in your browser.
Suggest a tool

Something missing?

Tell us what you need. We ship the top requests every two weeks.

Sent straight to the maintainers · no account needed
47 in queue·8 shipped this month
Request queued. Thanks!