Regex Tester | Online RegEx debugger
Free online regex tester with live validation, replace preview, explanation, multi-language code snippets, and templates to build and debug regular expressions faster.
Free online regex tester with live validation, replace preview, explanation, multi-language code snippets, and templates to build and debug regular expressions faster.
How to use
What is this for?
Quickly validate regular expressions in the browser: match list, replace preview, heuristic explanation, and copyable code samples—useful for form validation, log parsing, and text workflows.
Suggested workflow
- Enter a pattern and choose flags; optionally pick a template and refine it.
- Paste sample text into the editor; matches are highlighted with line numbers.
- Use Match for indices and groups; use Replace to preview then apply back to the editor.
- Use Explain for a walkthrough and Code to copy snippets in your preferred language.
Tips
- Flag g lists all matches; without g, engines typically surface the first match only.
- Explain is simplified; rely on Match for tricky nested or backtracking cases.
- Server-side languages may differ slightly from JavaScript regex; verify in your runtime.