Mockingbird — Privacy Policy

Last updated: 10 June 2026 · Applies to the Mockingbird Chrome extension.

In one sentence: Mockingbird has no server and collects nothing. Everything it captures or stores stays on your computer, and the extension makes no network requests of its own.

What Mockingbird does

Mockingbird is a developer tool that inspects, pauses, edits, and mocks HTTP traffic for a single browser tab that you explicitly arm. It runs entirely inside your browser. There is no backend, no account, and no sync.

Data we collect

None. We do not collect, transmit, sell, or share any data. There is no analytics, no telemetry, no crash reporting, and no remote logging. The developer of this extension never receives any information about you or your traffic.

Data the extension handles locally

Captured traffic: Requests/responses for the armed tab are held in memory and discarded when you disarm, close the tab, or restart the browser. They are never sent anywhere.
Rules & settings: Your mock and breakpoint rules and preferences are saved in chrome.storage.local — on your machine only.
Held-request state: A small list of currently-paused request IDs is mirrored to chrome.storage.session for reliability, and cleared automatically.
Capture history (opt-in): If you enable “Persist capture log,” a metadata-only snapshot (method, URL, status — no bodies) is kept in local storage so it survives a restart. You can clear it anytime.
Exports: HAR and rule-set JSON files are written only when you click Export, and only to the download location you choose.

The “debugger” permission

To pause and rewrite requests, Mockingbird uses Chrome’s DevTools Protocol via the debugger permission. Chrome shows a “Mockingbird is debugging this browser” banner whenever a tab is armed. This permission is used only to intercept traffic for the tab you arm — it is never used to read other tabs, browsing history, or stored credentials, and nothing observed through it leaves your machine.

Request replay

The replay/composer feature re-sends a request from the armed page’s own context. That request goes directly from your browser to the destination you specify, exactly as if the page made it. Mockingbird neither proxies nor records it beyond the in-memory capture log.

Permissions, briefly

debugger — pause/edit/mock traffic for the armed tab (the core function).
sidePanel — the extension’s UI surface.
storage — save rules/settings locally.
alarms — a keepalive timer so a paused request is never orphaned.
tabs — read the armed tab’s URL/title for scoping. No host permissions are requested.

Children

Mockingbird is a developer tool and is not directed at children.

Changes

If this policy changes, the “Last updated” date above will change with it. Because the extension collects nothing, changes will only ever clarify wording.

Contact

Questions about privacy? Reach out via the extension’s Chrome Web Store listing support link.