CheckNumber · Free Chrome tools

Private list tools that run in Chrome.

Generate test phone numbers and email addresses, or clean existing lists, without uploading source files. These extensions are utilities for QA and list preparation — they do not check whether a number or email account is live.

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Phone Number Generator

Generate 10,000–1,000,000 locally formatted test numbers by country or segment.

Chrome Web Store listing coming soon

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Email Generator

Generate 10,000–1,000,000 sample email addresses for forms, demos, and QA.

Chrome Web Store listing coming soon

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Phone Number Cleaner

Normalize, structurally validate, and deduplicate phone-number CSV or TXT files locally.

Chrome Web Store listing coming soon

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Email Cleaner

Remove malformed, disposable, and duplicate emails; domain routing checks are optional.

Chrome Web Store listing coming soon

Privacy by design

The generators and Phone Number Cleaner run locally. Email Cleaner optionally queries only email domains for mail-routing records; it never sends full addresses or file contents.

Read the extension privacy notice·Get support

How these tools work

  1. Install the tool from the Chrome Web Store when its listing is available.
  2. Generate a 10,000–1,000,000 record test list, or select a CSV/TXT file to clean.
  3. Copy or download the result. Your original file stays in your browser.

Product information updated August 2026. github.com/checkernumber