CellBar is an Android cellular signal meter. It reads what the device radio reports through Android's TelephonyManager and shows it plainly: live signal strength in dBm (RSRP on LTE/5G, RSSI on 3G/2G), RSRQ, SINR, ASU and timing advance, the network generation (2G/3G/LTE/5G, and LTE+5G on non-standalone networks), the band and downlink frequency computed from the channel number using 3GPP formulas, the carrier name, and the serving cell identity (Cell ID, PCI, TAC, MCC/MNC). It also reads the current Wi-Fi link (RSSI, channel, band, link speed) and nearby Wi-Fi networks through WifiManager. Free features: the complete live meter, a rolling 60-second signal graph, the serving cell details and the current Wi-Fi link. Paid features (CellBar Pro, an auto-renewing subscription sold through Google Play Billing with weekly, monthly and yearly plans, each with a free trial): recording an unlimited-length measurement session with statistics, "coverage walks" where the user walks and the app draws their own GPS track coloured by the signal measured at each point and marks dead spots, the list of neighbour cells, the full Wi-Fi analyser with channel congestion, and CSV export of any recorded session or walk via the Android share sheet. There are NO user accounts, NO login, NO registration. The app has no backend of its own for measurements. Permissions used: ACCESS_FINE_LOCATION and ACCESS_COARSE_LOCATION (required by Android before it will reveal cell identity information at all, and used to draw the user's own coverage walk), ACCESS_WIFI_STATE and CHANGE_WIFI_STATE (Wi-Fi analysis), INTERNET and ACCESS_NETWORK_STATE (required by the Google Play Billing library for purchases, and by an optional remote configuration fetch). The app cannot and does not amplify or improve signal; it is a measuring instrument only.