Regex Tester & Debugger

How to test and debug regular expressions

1. 1Select a pre-built template from the preset bar (e.g. Email, IPv4, URL, Strong Password) or type your custom pattern.
2. 2Toggle regex flags (g for global, i for case-insensitive, m for multiline) directly beside the expression box.
3. 3Paste your sample text into the test payload area to inspect matched substrings and capture groups instantly.
4. 4Switch to the 'Replace' tab to preview dynamic string substitutions using placeholders like $1, $2, or $&.
5. 5Switch to 'Generate Code Snippet' to export production code for JavaScript, Python, Go, or PHP.

Architecture & Privacy

• 100% In-Browser Engine: Safe testing of sensitive user logs, passwords, and tokens with zero cloud uploads.
• Real-Time Capture Group Inspection: Displays full matches, starting indices, lengths, and numbered/named capture groups.
• Catastrophic Backtracking Protection: Loop-capped execution avoids browser UI freezing on complex nested quantifiers.
• Pre-Built Enterprise Presets: 20+ audited production patterns for email, IPv4, URLs, phone numbers, and dates.