v157 · web bluetooth
MTU probe
Read the real negotiated write size off a real device. Web Bluetooth needs a user gesture, a secure context, an adapter, and a device in range — so this page is explicit about which of those it has, rather than reporting a number it made up.
What this browser has
- navigator.bluetooth
- —
- Property on prototype
- —
- Secure context
- —
- Adapter available
- —
Pair a device and read the size
This opens Chrome's device chooser. Pick any BLE device in range; the page connects its GATT server, reads the negotiated write size, and disconnects. It writes nothing to the device.
- Device
- not connected
- Max write size
- —
- vs the 20-byte assumption
- —
- Size changes seen
- 0
Log
- Nothing yet.
code path
const device = await navigator.bluetooth.requestDevice({
acceptAllDevices: true,
optionalServices: [],
});
const server = await device.gatt.connect();
// The number this feature adds. Undefined before Chrome 157.
const max = server.maxWriteWithoutResponseSize;
// Feature-detect on the prototype, not on a value: the property can
// legitimately be undefined on a disconnected server.
const supported = "maxWriteWithoutResponseSize" in
BluetoothRemoteGATTServer.prototype;