Regex Tester
Write a JavaScript regex and see matches highlighted directly inside the test text as you type, with capture groups, named-group tables and match offsets. Explain the pattern token by token, look up syntax in the cheat sheet, save named patterns, export matches as CSV or JSON, and copy equivalent code for JavaScript, Python, PHP, Go and Java. Supports all flags including d (indices) and v (unicode sets), with a time budget that stops catastrophic backtracking from freezing the page.
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How to use Regex Tester
- 1Type the pattern between the slashes and toggle flags (g i m s u v y d) — matches highlight in the test text immediately.
- 2Use the Match tab for the match/group table, Replace with $1 / $<name> substitutions, or Split.
- 3Open Explain to read the pattern token by token, or the Cheat sheet for syntax and flag reference.
- 4Save patterns you reuse; export matches as CSV/JSON; grab ready-to-run code from the Code tab.
About Regex Tester
Write a JavaScript regex and see matches highlighted directly inside the test text as you type, with capture groups, named-group tables and match offsets. Explain the pattern token by token, look up syntax in the cheat sheet, save named patterns, export matches as CSV or JSON, and copy equivalent code for JavaScript, Python, PHP, Go and Java. Supports all flags including d (indices) and v (unicode sets), with a time budget that stops catastrophic backtracking from freezing the page.
Regex Tester is part of FizzKit — a collection of focused developer and ad-tech tools. Because everything runs locally, it works offline once loaded and never exposes your data to a remote server.