regex online tester
Test regular expression matching
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Quick start: Regex Tester in 3 steps
- Enter a pattern and sample text
- Toggle flags (g/i/m, …) and inspect highlights
- Copy the verified pattern into your code
Regex Tester: curated examples
- •Example: rough email check with `^[\w.-]+@[\w.-]+\.\w+$` (still validate server-side).
- •Example: debug capture groups before using `$1` in a replace template.
About Regex Tester
Run a regular expression against sample text and see highlighted matches, capture groups, positions, and counts. Test replacements and adjust flags with syntax feedback as you work.
Use the regex engine of your target language as the final authority; support for lookbehind, Unicode, and flags differs by language.
How Regex Tester works
When you need to see exactly what matched and which group captured it, an interactive sample reveals edge cases faster than repeatedly running an application. Before shipping a rule, still test it in the target language with realistic data.
Regex is a poor parser for nested JSON, HTML, or large untrusted input; some patterns can cause catastrophic backtracking. Prefer a parser for those jobs, or limit input size and execution time.
Why use Regex Tester on WoDeTool
WoDeTool keeps Regex Tester, related utilities, clipboard detection, and pipelines together, so you can work through JSON, JWT, and Diff in one workspace.
Use Smart Clipboard on the home page to auto-detect pasted JSON, Base64, or JWT and jump to Regex Tester. Save a tool pipeline to chain Regex Tester with related utilities. Read our guides for real-world workflows.
Common use cases
- •Validate an email field: Try ^[^\s@]+@[^\s@]+\.[^\s@]+$ against user@example.com and user@.
- •Extract a log ID: Run request_id=(\w+) on request_id=ab12cd34 status=500 and inspect capture group 1.
- •Normalize a phone number: Replace \D with nothing in 138-0013-8000 to preview the cleaned value.
Related tutorials
Frequently asked questions
- Is Regex Tester free to use?
- Yes. Regex Tester on WoDeTool is completely free with no sign-up required. Open the page and start using it immediately.
- Which regex flavor is supported?
- JavaScript RegExp (browser-standard). Flags g/i/m/s/u are supported; very large inputs may slow on complex patterns.
- Why do results differ from Python regex?
- Engines differ on \w, boundaries, and lookaheads. Test in your target runtime for cross-language patterns.
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