JSON Formatter & Validator
Validate JSON and format it for reading or compact transfer.
DeveloperDeveloper tools
Regex Tester
Test JavaScript regular expressions in an isolated worker.
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How to use regex tester
- Enter Pattern without surrounding slash delimiters.
- Set unique JavaScript Flags and enter representative Test text.
- Select Process input and inspect each returned index, text, and capture-group array.
Work through an example
Enter a delimiter-free JavaScript pattern, inspect capture groups and indexes, and understand the worker timeout and match cap.
Test JavaScript regex captures with a bounded example →Formats, privacy, and practical limits
This tool processes the values you enter in your browser. No account or upload to ERITHRA is required.
Files and generated results exist only for this tab session. Download any result you want to keep before leaving the page. Browsers may use temporary memory or disk cache while processing.
Frequently asked questions
Why did my test stop after one second?
Matching runs in an isolated worker with a one-second safety timeout. Simplify the expression or reduce the sample before retrying.
Why do I see only one match?
A pattern without global or sticky matching returns its first match. Use g for a normal global scan when that is the intended behavior.