Browser-internal pages use special schemes such as about:, chrome://, and edge://. They are handled by the browser rather than a normal website. about:blank is standardized; most other internal addresses are browser-specific.
What the about: scheme is
In an ordinary URL, the scheme before the colon—usually https:—tells software how to access a resource. The registered about: scheme identifies information or resources related to the browser or application itself. It does not contain a hostname.
RFC 6694 establishes the scheme and reserves about:blank as the well-known identifier for a blank page. Beyond that shared baseline, browsers are free to expose different internal pages and may redirect about: aliases to their own privileged schemes.
Why about:blank is special
Every modern browser needs an interoperable empty document. New frames and windows can start with an initial blank document before another navigation commits. Users can also type the address directly or choose a blank homepage.
“Blank” describes the initial document, not every possible developer context. A page can create an about:blank popup or frame, inherit an origin, and write content into it. That is why security claims such as “an about:blank window can never contain code” are too broad.
The main internal URL families
| Family | Common browser | Purpose |
|---|---|---|
about: | Shared concept; especially visible in Firefox | Registered browser-related scheme, including standardized about:blank |
chrome:// | Google Chrome and Chromium | Privileged settings, history, downloads, extensions, diagnostics, and browser UI |
edge:// | Microsoft Edge | Edge-specific versions of settings, policy, downloads, extensions, and diagnostics |
about: pages in Firefox | Firefox | Settings, profiles, support information, configuration, networking, and other diagnostics |
| Safari settings UI | Safari | Safari exposes fewer user-facing internal URL commands and emphasizes native settings panels |
Useful examples, with browser boundaries
| Task | Chrome | Edge | Firefox |
|---|---|---|---|
| Settings | chrome://settings | edge://settings | about:preferences |
| Downloads | chrome://downloads | edge://downloads | about:downloads |
| Extensions/add-ons | chrome://extensions | edge://extensions | about:addons |
| Version information | chrome://version | edge://version | about:support for detailed support data |
| Blank document | about:blank | about:blank | about:blank |
Use these addresses by typing them yourself. A normal website should not need you to paste an unknown internal command to unlock content or “prove” your browser is safe.
Why a command from one browser may fail in another
Internal pages are product interfaces, not ordinary web standards. Chrome may map some about: aliases to chrome://, while Edge uses edge:// and Firefox provides its own about: set. A fun or diagnostic command mentioned in a tutorial can be removed, renamed, or unavailable on mobile.
This is why the old advice to type about:about as a universal catalog is incomplete. It is useful in Firefox; Chromium-based browsers have their own internal-page lists, and Safari does not mirror that model for users.
Developer context: initial blank documents and origin
A new browsing context begins with an initial empty document. An iframe without a usable src can load about:blank, and window.open() may create a blank context before the requested URL loads asynchronously. The creator can sometimes write content into that document.
Origin behavior is context-dependent. An about:blank document created within a page can inherit the creator's origin, while a user entering the address directly creates a different context. Developers should use the platform's defined checks rather than assuming every string beginning with about:blank is identical.
Also distinguish about:blank from HTML's target="_blank". The first is a URL; the second asks the browser to use a new browsing context for a link or form.
Safety and privacy notes
- Internal pages can expose sensitive diagnostic information. Do not post full screenshots of profile paths, policies, command lines, or identifiers without reviewing them.
- Do not change experimental flags or advanced configuration values unless you understand how to reverse them.
- On a managed device, policy pages are useful for visibility but are not permission to bypass controls.
about:blankitself requests no remote webpage, but browser sync, extensions, updates, and background services can still use the network.
For official definitions, see RFC 6694, Chromium's special-URL documentation, and MDN's inherited-origin explanation.