Unlimited Regex

Write the pattern, watch it match, understand why.

macOS iOS iPadOS

Type a regular expression and see every match highlighted as you type. When the pattern does not do what you meant, the app explains what it actually does — piece by piece, in plain language — and shows you the engine’s own view of it.

Match as you type

• Live highlighting — every match across the whole text, with every capture group coloured and numbered.
• A match list — each result with its position and all its groups, including named ones.
• Replace with a preview — see the result before you commit. Backreferences and case-conversion escapes work.
• Every mode — split, find-all, and match-at-position.

Understand the pattern

• Plain language — every part of the pattern explained: this is a lazy quantifier, this group does not capture, this class matches any digit.
• A railroad diagram — the pattern drawn as a track. A fork is a choice; a line that doubles back is a repeat. Export it as SVG or PNG.
• A backtracking trace — step through the engine’s decisions on your own text.
• Warnings that matter — catastrophic backtracking, an unescaped dot, an anchor that can never match.

Every flavour

• Thirteen flavours — PCRE2, JavaScript, Python, Java, .NET, Go, Rust, RE2, Perl, POSIX basic and extended, legacy PCRE, and RE#, with the differences between them called out.
• Convert between them — the app notes every construct that cannot survive the trip.
• Flags, live — case-insensitivity, multiline, dot-matches-newline, and Unicode. The effect shows immediately.

Built for real work

• Fast on real text — a lazy DFA keeps up with megabyte subjects while you type.
• Catastrophic backtracking, caught — the app warns you that a pattern is dangerous before it locks up a production job.
• A library of your own — save patterns with notes and test subjects. The regex you worked out last year still has its tests attached.
• Entirely offline — nothing you paste leaves the device.

One purchase, every device