Regex Validator
Regex Validator — check regex syntax online.
- Runs in your browser
- Free, no signup
Regex engine:
JavaScript
Your files are processed locally in your browser and are not uploaded to our server.
A regex validator is an efficient way to catch mistakes before you test a pattern against real data.
This checks the pattern using JavaScript’s own RegExp parser so the result matches browser behaviour.
How to use this tool
- Paste your regex into the field.
- Review the pass/fail status and browser error if it is invalid.
- Use the tester for runtime matching examples when the pattern is valid.
Frequently asked questions
Does it work exactly like the browser?
Yes. It uses the JavaScript RegExp engine, which is the same engine used when the pattern runs in browser-based code.
What if the pattern contains unsupported syntax?
The validator reports the parsing error rather than a stack trace, which keeps the message useful without exposing internal implementation details.