Feature Flag Scanner

About

Feature Flag Scanner is a developer and QA tool for inspecting feature flags that a website exposes to the browser.

Open the extension on a page to scan browser-visible sources such as page markup, inline scripts, localStorage, sessionStorage, readable cookies, script URLs, and common feature flag globals. Results include the detected flag name, current value, source, evidence, pattern, and confidence.

You can search results by name, value, source, evidence, or override status. When a client-visible flag needs testing, save a local override and reload the page. Overrides are stored locally per site origin and reapplied on later page loads where the page uses writable browser-visible values.

Common uses include QA rollout verification, frontend branch testing, experiment debugging, SDK trace discovery, and support reproduction sessions where visible flag state matters.

This extension runs locally in the browser. It does not send scan results or overrides to any server.

Limitations:

  - It cannot inspect server-side flags.
  - It cannot read HttpOnly cookies.
  - It cannot modify private SDK internals unless the page exposes writable values.
  - A saved override only affects a site if the site reads the client-visible value that the extension can write.
  - Sites may overwrite local values after load if their application code fetches fresh flags from an API.