Regex Tester
Test regular expressions with live pattern matching, multi-language support, and advanced debugging features. The best regex testing tool for developers.
Introduction
Regex Tester gives you pragmatic, language‑aware pattern testing. Validate in JavaScript for free, then switch engines (Python, Java, Go) with premium to understand dialect differences before code hits production.
Live match highlighting, group breakdowns, and performance timing help you iterate safely and avoid catastrophic backtracking.
Key features
- JavaScript regex testing
- Real-time pattern matching
- Match highlighting
- Basic flags support
- Sample patterns
- Match details with groups
How it works
Enter a pattern and test text. The engine compiles the expression, reports errors inline, and highlights all matches and groups. Engine switching (premium) re‑evaluates the same pattern with dialect‑specific rules to surface portability issues.
Step-by-step usage
- Choose an engine (JavaScript by default).
- Enter your pattern and flags; paste sample input.
- Review groups, positions, and timing.
- (Premium) Switch engines or run bulk tests and export results.
Examples
Validate email-like strings (JS)
/^[^\s@]+@[^\s@]+\.[^\s@]+$/Extract ISO dates
/\b(\d{4})-(\d{2})-(\d{2})\b/gReplace tabs with two spaces
const out = input.replace(/\t/g, ' ')Security & privacy
Where applicable, processing runs locally in your browser. Inputs are not logged or sent to external services. Premium features inside the app use Supabase Auth to protect access. For sensitive work, prefer local files and avoid sharing secrets. Outputs include copy and download actions to minimize manual transcription errors.
Accessibility
The tool supports keyboard navigation and screen readers with ARIA labels and descriptive messages. Focus order is logical, and error messages use human‑readable language. These docs maintain proper heading hierarchy and color contrast, and the app version includes skip links and live regions where appropriate.
Limitations & disclaimers
Some advanced capabilities are available only in the DevToolsKitHub app with a premium plan. The static documentation does not execute code or store inputs. Where behaviors differ across runtimes (browsers, servers, language engines), treat outputs as representative examples.
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