How it works
Connects the browser to a Bluetooth Low Energy device and shows its full GATT tree: every primary service, the characteristics it contains, the operations each one supports (read, write, notify or indicate) and the associated descriptors, with the 128-bit UUID and the short 16-bit identifier whenever the element is standard.
Readable values are read automatically and decoded following the Bluetooth SIG specification: battery level comes out as a percentage, the Device Information service as manufacturer, model, serial number and firmware, hardware and software revisions, and the PnP ID as the pair of manufacturer and product identifiers. Anything without a defined meaning is shown as text, as a number or as a hex dump.
You can also subscribe to characteristics that send notifications to watch them change live — a heart rate, a temperature, a counter — and export the whole walk as JSON. The tool only reads: it never writes to the device. All communication happens between your computer and the peripheral through the Web Bluetooth API; nothing travels to a server.
Examples
0x180F → 0x2A195B → 91 %The Battery service exposes a single byte with the remaining charge, so 0x5B equals 91 %.0x180A → 0x2A50 (PnP ID)USB Implementers Forum · VID 0x046D · PID 0xC52B · v1.0.0The PnP ID identifies the manufacturer and the product with the same codes USB uses, so you can look them up in the usb.ids catalogue.6e400001-b5a3-f393-e0a9-e50e24dcca9eNordic UART Service128-bit UUIDs belong to vendor-specific services; the most widespread ones, such as Nordic’s serial port, are shown with their name.Use cases
- Check how much battery a sensor, a scale or a wearable has left without installing the manufacturer’s app.
- Look up the model, serial number and firmware version of a device before updating it or opening a warranty claim.
- Verify during firmware development that the peripheral advertises the expected services and characteristics, with the right properties.
- Discover the UUID of a vendor-specific characteristic so you can use it from your own application.
- Check live that notifications arrive, and how often, when an application is not receiving data.
- Document a device’s full GATT tree by exporting it as JSON to attach to a report.
Frequently asked questions
Why does it not work on my iPhone or in Firefox?
The Web Bluetooth API is implemented in Chromium-based browsers — Chrome, Edge and Opera — on Windows, macOS, Linux, ChromeOS and Android. Firefox and Safari do not implement it, and on iOS every browser uses the system engine, so it is not available there either. HTTPS is also required, and Bluetooth must be switched on.
The device is on but does not show up in the list.
There are usually three reasons: the peripheral is already connected to another application or computer and stopped advertising; it is not in discoverable mode, which on many devices is enabled by holding a button; or the chosen filter is too narrow. Try the option that offers every nearby device and move closer.
Why do I see fewer services than in a native application?
A web page can only see the services it requested before connecting, which is why the tool asks for every standard one and lets you add the vendor-specific UUIDs you know. The browser also keeps a security blocklist — including human interface devices (HID) and firmware update services — that no page is allowed to read.
What do a characteristic’s properties mean?
Read means the value can be requested whenever you want. Write and write without response mean the device accepts data, with or without confirmation. Notify and indicate mean the device itself sends the value when it changes; the difference is that an indication requires the client to confirm, which makes it slower but safer.
Why do some elements have a short UUID and others a very long one?
16-bit identifiers such as 0x180F or 0x2A19 are reserved by the Bluetooth SIG and have a meaning defined in the specification, so the tool shows them with their official name. A 128-bit UUID belongs to the manufacturer: only its own application knows what it holds, although the content is still shown as text, as a number or as hexadecimal.
Can the tool write or change anything on the device?
No. It only reads values and enables the notifications you choose, which is a subscription and not a change to the device’s configuration. It never writes to a characteristic, so there is no risk of leaving the peripheral in an unexpected state.
Does the device data leave my computer?
No. The connection is handled by the browser against your computer’s Bluetooth adapter, and no value that is read is sent to a server. You grant permission device by device from the browser chooser, and you can revoke it whenever you want.