Regex tester

Find matches and capture groups.

On your device · No account

Privacy details

Regex tester processes your input in this browser. Inputs and results are excluded from analytics. Recent tools save tool names, visit counts and last-visit times. Saved tools store only their names. Draft saving is optional and stays on this device; delete saved text with the draft controls. Loading text from a URL is optional and contacts that server; its URL and your IP address are visible to the server. An optional “Use in” action keeps a handoff in this tab. The next tool removes it on arrival and ignores it if more than a minute has passed.

Copy link includes the inputs you choose to share in the address. Anyone with that link can reopen them. Files and generated results are excluded. Password and key tools share settings only.

Your input

Regular expression

Options and local file

Flags

Open a text file on this device

Optional settings apply only to this tab.

Your result

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Links include your inputs and settings. Anyone with the link can see them, so leave out private text. Files and generated results are left out; random draws run again.

Keyboard shortcuts

Updated 2026-09-20

Regex tester explained

Run a JavaScript regular expression against local text and inspect each match, capture group and starting index. Global and sticky flags determine whether matching continues. A separate worker stops patterns that take too long.

Next: JSON formatter

A worked example

OCT-(\d+) applied to OCT-42 matches the whole code and captures 42 as the first group. Match indexes count UTF-16 code units from zero.

Before you use the result

Uses this browser’s JavaScript regex grammar, not PCRE, Python or .NET. Timeout and match limits prevent runaway jobs. Results never claim that a pattern is safe for a production service.

Cite this page

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ToolOctopus. “Regex tester.” Updated 2026-09-20. https://tooloctopus.com/regex-tester-tool.

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