Bluetooth Signal Tester

What this Bluetooth tester does

This tool uses the browser's Web Bluetooth API to scan for and connect to nearby Bluetooth Low Energy (BLE) devices like fitness trackers, heart-rate monitors, smart scales, beacons, headphones, and IoT sensors. Once connected it walks the device's GATT (Generic Attribute Profile) table, listing every service and characteristic it is allowed to see, reads static values like battery level and manufacturer information, and, where the platform allows, monitors the RSSI signal strength of the device's advertisement packets.

What is RSSI and why is it negative?

RSSI (Received Signal Strength Indicator) is measured in dBm and is always negative: a value closer to zero (e.g. -45 dBm) means a strong, nearby signal, while a lower value (e.g. -90 dBm) means the device is faint or far away. This tester normalizes RSSI into a 0-100% quality bar and tracks the minimum, maximum, and average over the session so you can gauge range, find a beacon, or debug flaky connections. Live RSSI depends on the operating system and an experimental browser flag, so it isn't available everywhere, but GATT inspection works regardless.

Browser support & permissions

Web Bluetooth works in Chrome, Edge, and Opera on desktop and Android; Firefox and Safari (including every browser on iOS) do not support it. For security, the browser only lets a page access a device the user explicitly picks, and only the standard GATT services the page requested in advance. Vendor-specific services are hidden by design, so some devices reveal little. Nothing happens without your click.

Private by design

All scanning, connecting, and reading happens locally between your browser and the device over Bluetooth. No device names, identifiers, or readings are ever sent to a server. The optional JSON export is generated in your browser and saved straight to your machine.