Developer

Regex tester

Test JavaScript regular expressions locally, highlight matches and inspect capture groups or replacements.

Local · JavaScript engine
Flags

Positions use UTF-16 code units, matching JavaScript. The global flag finds all matches; without it, only the first is returned. Empty matches are marked with a caret. Up to 128 KiB of UTF-8 text and 1,000 matches; each test runs in an isolated worker with a two-second timeout.

How to use Regex tester

  1. Choose your TXT or paste text into the editor.
  2. Enter a pattern without slash delimiters, set flags and add test text. Live testing is optional.
  3. Inspect matches, named groups and UTF-16 positions, preview replacements or download a JSON report.

Formats and requirements

Input formats
TXT
Output
JSON
Availability
Free in your browser and through the CLI
Files per operation
1
Browser file limit
0.13 MiB per file, 32 MiB total

What to expect

Tests JavaScript regular expressions locally with captures, named groups, UTF-16 positions and replacement. Up to 128 KiB of text, 1000 matches and 1 MiB of output. Execution is time limited; the CLI requires Node.js.

Do my files leave my device?

No. Thanks to advanced file-processing technology, your files are processed directly on your device, inside your browser. OneKit does not receive your input files or results. Required public processing libraries may download when you first use the tool.

File privacy and local processing →

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