A small web app to test, explain, and learn regular expressions. Everything runs on the browser's native JavaScript RegExp engine; no data is sent to any server.
- Real-time tester – matches highlight as you type, with per-match groups, named groups, and indices
- Flags – g, i, m, s, u toggles with plain-language tooltips
- Explainer – break any pattern down token by token in plain English
- Pattern library – ready-to-use patterns for emails, URLs, phones, IPs and more, with one-click copy
- Substitution – preview find-and-replace with capture-group references
- Cheat sheet – quick reference for characters, quantifiers, anchors, groups, and flags
- Bilingual – English and Chinese UI
npm install
npm run devOpen http://localhost:3000.
npm run buildStatic export to out/.
Licensed under the GNU Affero General Public License v3.0 — see LICENSE.
Free to use, modify, and self-host. If you run a modified version as a network service, you must open-source your modifications (AGPL §13). For commercial licensing without copyleft obligations, contact support@shuttlelab.org.