Developer tools
Regex Tester
Test a JavaScript regular expression against sample text. Nothing you enter leaves your browser.
Your result will appear here.
What this tool does
About the Regex Tester
Test a JavaScript regular expression against sample text. It is intended for development and debugging workflows where a small, inspectable transformation is faster than setting up a script.
The tool checks the supplied value and reports validation details so you can correct the source rather than guessing where it failed.
How to use it
- Pattern, then --- on a line, then test text in the input pane. Use the example button if you want to see the expected syntax.
- Review the input for the structure shown in the example. Then select “Test regex.”
- Inspect the result for warnings or structural differences, then copy it into the destination system.
Practical example
Start with a known input
Try this sample input: /hello/gi --- Hello, hello world! Select “Test regex” and compare the result with the source before using it elsewhere.
What to know about the result
- Processing happens in this browser. Your entered text and selected files are not sent to FormatCalc for conversion.
Common questions
Using the Regex Tester
Is the Regex Tester free to use?
Yes. FormatCalc's Regex Tester is free to use with no account required.
Is my data private when I use the Regex Tester?
Yes. This tool processes your input locally in your browser. FormatCalc does not upload or store what you enter.
How do I use the Regex Tester?
Paste or type your input, select any available options, and choose Test regex. You can then copy the result.
What should I check before using the result?
Processing happens in this browser. Your entered text and selected files are not sent to FormatCalc for conversion.