Regex Tester
Test regular expressions with live match highlighting and capture groups.
Getting a regular expression right usually takes several rounds of tweak and retry. The Regex Tester re-runs your pattern on every keystroke and shows each match, its position and its capture groups. It runs in the app on your machine, so log lines and customer data you test against stay local.
Live matching
Matches update as you edit the pattern, flags or test string. An invalid pattern shows the engine's error message instead of results.
Highlighted matches
Every match is marked in the test text, cycling through four colors so adjacent matches are easy to tell apart.
Match details
Each match lists its text, its position in the string and the numbered capture groups.
Editable flags
Type any flags into the flags field. A reference below it covers g (global), i (case insensitive), m (multiline) and s (dot matches newlines).
Common pattern presets
Load a starting point for emails, US phone numbers, URLs, IPv4 addresses, dates, HTML tags, hex colors and card-number formats, each with sample text.
Copy results
Copy the pattern as /pattern/flags, or copy all matches with their positions and groups.
Which regex flavor does the Regex Tester use?
It uses the JavaScript RegExp engine built into the app, so syntax and flags follow JavaScript behavior. Other flavors such as PCRE or Python may differ on some features.
Can I see capture groups?
Yes. Each match in the details list shows its position and the numbered capture groups it produced.
Generate random strings with custom length and character sets.
Open →Side-by-side text diff with word-level highlights and a JSON mode.
Open →Escape and unescape HTML, JSON, backslash, shell and unicode strings.
Open →No card, no account. Every tool included, bought once.