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Build, test and debug regular expressions with live highlighting, an explain panel and a replace mode.
Test regular expressions against your own text with live match highlighting, per-match capture groups, a plain-English explain panel and a replace mode. Runs entirely in your browser using the JavaScript RegExp engine. Nothing is uploaded.
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Regular expressions are powerful but hard to read back once written. This tester highlights every match live as you type, breaks each match down into its numbered and named capture groups, and explains a valid pattern in plain English so you can see exactly what each token does. It also has a replace mode, a common pattern library and freeze protection against catastrophic backtracking.
Matches are marked in the text as you type, alternating colours for adjacent hits.
Every token in a valid pattern gets a description, indented to show nested groups.
Switch to replace mode with $1, $<name> and $& support, previewed live.
Load a ready-made pattern for email, URL, UUID and more, or insert tokens from the cheatsheet.
Matching runs in a background worker with a timeout, so a runaway pattern never locks the tab.
Copy a link that carries your pattern and test text in the URL hash. Nothing is sent to a server.
Type or paste a regex pattern into the Pattern field and toggle flags like g, i or m.
Paste the text you want to test against. Matches highlight live as you type.
Expand a match to see its index, start-end span, and every numbered and named capture group.
Open the explain panel to see what each token in your pattern does, in plain English.
Switch to Replace to preview a substitution using $1, $<name> or $&.
Copy the pattern as a JavaScript literal, RegExp constructor or Python code, or generate a private share link.
Matching runs in a Web Worker inside your browser using the JavaScript RegExp engine. Your pattern and test text are never uploaded to a server. The share link stores them in the URL hash, which browsers never send to a server either.
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Convert text between UPPERCASE, lowercase, Title Case, camelCase, snake_case, kebab-case and more. Perfect for developers, writers, and anyone who needs to quickly change text case.
Developed by MadMVP
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