WEBCAT

Verifiable code for the web

WEBCAT helps people trust the websites they use by making it possible to verify the code running in their browser.

Get the Browser Extension For Developers

The Problem

Today, even if a website uses HTTPS, users usually have no way to know whether the JavaScript code they receive has been modified - by a compromised server, a malicious update, or a third party.

How WEBCAT Works

Developers publish manifests to their frontend code
Independent infrastructure records those manifests, making them auditable and difficult to silently change
The WEBCAT browser extension verifies that the code running in their browser matches what the site intended to publish.

News

WEBCAT: Towards auditable web application runtimes December 18, 2025
Introducing WEBCAT: Web-based Code Assurance and Transparency March 19, 2025

Resources

Browser Extension

Verify what code your browser is running

View Repository

Enrollment Infrastructure

Public, auditable infrastructure for enrollment data

View Repository

Specifications

How WEBCAT works, in detail

View Specifications

Developer CLI

Tools for integrating WEBCAT into your workflow

View CLI

For Developers

If you're building with WEBCAT, these resources will help you get started.

Enroll now Read the CLI docs View the specifications