PCRE Regex Tester

Test classic PCRE (Perl-compatible) patterns — the flavor used by PHP < 7.3, older Apache configs, and legacy tools.

Free, no signup — runs entirely in your browser on RegexEditor.dev.

PatternRegular Expression Pattern

Flavor

Test String

Annotation

Unable to parse pattern

Active Flags:

gglobal: Don't return after first match

iignore case: Case insensitive matching

Match Results

0 matches

No matches found

Quick Reference

Test your PCRE regex in the editor below

PCRE regex: what makes it different

Lookaround & backrefs: Full Perl-compatible lookaround, backreferences, and recursion support.
Legacy safety: PCRE 8.x lacks PCRE2's improved heap limits — catastrophic backtracking protection must come from your own timeouts.
Delimiter style: In PHP's preg_* functions the pattern is wrapped in delimiters (/…/i); test the inner pattern and flags separately here.

Classic PCRE (the 8.x series) remains the regex flavor of record for a huge amount of legacy software: PHP before 7.3, older Apache httpd, many Unix tools, and long-lived config formats. It is almost PCRE2, but with subtle behavioral differences that only show up when you test against the real thing.

This tester runs the PCRE engine compiled to WebAssembly. If you maintain legacy PHP or tooling pinned to PCRE 8.x, validate patterns here against the same library version family your production systems use.

PCRE regex FAQ

Is classic PCRE still used?

Yes. PHP before 7.3, many legacy Apache modules, older nginx builds, and numerous long-lived tools link against PCRE 8.x. If your production system pins that library, test against it rather than PCRE2 to avoid subtle drift.

What is the difference between PCRE and Perl regex?

PCRE aims for Perl 5 compatibility but is not exact: some Perl features (like code-embedded patterns (?{…})) are unavailable, and PCRE adds its own extensions. For day-to-day patterns the syntax is effectively the same.