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Regex Generator & Explainer

Generate a regular expression from example strings and explain any regex piece by piece in plain English. Rule-based, runs in your browser.

No uploads

  • ✓ Generalised from your examples · matches 3/3, rejects 2/2

    ^\d{4}-\d{2}-\d{2}$

  • ✓ ISO date (YYYY-MM-DD) · matches 3/3, rejects 2/2

    ^\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[01])$

  • ✓ Exact alternatives · matches 3/3, rejects 2/2

    ^(?:2024-01-15|1999-12-31|2026-10-14)$

How to use Regex Generator & Explainer

  1. 1Open Regex Generator & Explainer. It runs in your browser, no sign-up.
  2. 2Type or paste your input.
  3. 3Copy or download the result.

Questions

How is the regex generated?

Your examples are split into runs of digits, letters and punctuation. If they share a structure, those runs become character classes with lengths; common formats like emails, dates and UUIDs are also checked against your examples.

Is AI involved?

No. It is rule-based and runs entirely in your browser.

Which regex flavour?

JavaScript (ECMAScript). Most patterns also work in PCRE, Python and Go.

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