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Preview of WEBCAT

WEBCAT by Freedom of the Press Foundation

WEBCAT verifies the integrity and transparency properties of web applications on participating domains by ensuring that the code running in the browser matches the publisher’s auditable commitments.

Experimental
Available on Firefox for Android™
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Successful verification of a test domain hosting the Element Matrix web client.Failed verification and blocking of a test domain.
About this extension
Warning: This is experimental software and currently released as an alpha. It might slow down or interfere with web pages, and it might not yet provide the intended security guarantees.

WEBCAT verifies the provenance and integrity of web applications directly in your browser.
For the extension to be effective, a website owner must configure their domain and application to work with WEBCAT.

The extension does not affect websites that are not enrolled in the system and does not interfere with normal browsing. Protection is active only when a green icon appears in the top-right corner of the address bar. If an enrolled website fails validation, its content is blocked and a clear error page is displayed.

WEBCAT is currently experimental, and users are encouraged to report any issues.

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Permissions and data

Required permissions:

  • Access browser tabs
  • Access browser activity during navigation
  • Access your data for all websites

Data collection:

  • The developer says this extension doesn't require data collection.
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More information
Version
2.6.2
Size
89.24 KB
Last updated
3 days ago (Mar 1, 2026)
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