The Network Information API is a browser API that exposes details about your device's network connection: whether you are on Wi-Fi, cellular, or ethernet, and the effective quality of that connection. You can see your connection type on whatsmy.fyi.
What Is the Network Information API?
The Network Information API (navigator.connection) is a browser API that provides read access to information about the network connection in use by the device. It is part of the W3C Network Information specification.
The API exposes:
type: The type of connection βwifi,cellular,ethernet,bluetooth,wimax,other,unknown, ornone.effectiveType: The effective connection quality based on recently observed RTT and throughput:slow-2g,2g,3g, or4g. Note: "4g" means a fast connection, not necessarily an actual 4G cellular connection.downlink: Estimated effective bandwidth in Mb/s.rtt: Estimated round-trip latency in milliseconds, measured at the application layer.
Connection Types Explained
- Wi-Fi: Wireless connection to a local network router, which connects to the internet via your ISP.
- Cellular: Mobile data connection (3G, 4G LTE, 5G) through a mobile network operator.
- Ethernet: Wired connection directly to a router or network switch. Generally the most stable and lowest-latency connection type.
- Unknown: The browser cannot determine the connection type. This is common in desktop browsers that do not implement the full API.
Effective Connection Type vs. Actual Connection Type
The effectiveType value (slow-2g, 2g, 3g, 4g) is determined by measuring actual performance, not the connection label. A phone on an LTE (4G) network in a weak signal area might show 3g or even 2g effective type because actual throughput is low.
Conversely, a fast Wi-Fi connection shows 4g effective type even though it is not cellular. The 4g label means "fast" β it is a performance tier, not a technology descriptor.
Browser Support
The Network Information API has inconsistent browser support:
- Chrome and Chromium-based browsers (Edge, Opera, Brave): Full support including
type,effectiveType, anddownlink. - Firefox: Limited support β
effectiveTypeis available buttypeis not. - Safari (iOS and macOS): No support as of 2025. The connection type will show as "Unknown" on Safari.
If whatsmy.fyi shows "Unknown" for your connection type, it most likely means you are using a browser that does not implement the Network Information API.
Privacy Implications
The Network Information API adds another data point to your browser fingerprint. Knowing whether you are on Wi-Fi or cellular, combined with your screen resolution, timezone, and user agent, can help narrow down your device type and context.
Some privacy-focused browsers and extensions suppress or randomise the Network Information API to reduce fingerprinting risk.
Frequently Asked Questions
Why does my Wi-Fi connection show as "Unknown"?
If you are using Safari or a browser without Network Information API support, the connection type cannot be determined and shows as "Unknown". This does not indicate a problem with your connection.
What does "effective: 4g" mean?
It means your connection's effective quality β measured throughput and latency β is classified as fast. The 4g effective type applies to any connection with downlink > 10 Mbps and RTT < 80ms, whether it is cellular, Wi-Fi, or ethernet.
