Phido — BLE Alert Device
Never Leave Behind What Matters — A Bluetooth Smart Device & React Native App That Alerts You When You Walk Away Without Your Essentials
Case Details
Product: Phido — BLE Proximity Alert Device
Client: Specific Client — Confidential
Type: IoT Hardware + Companion App
Protocol: Bluetooth Low Energy (BLE)
Range: 15–20 metres (BLE-dependent)
App Stack: React Native (Android & iOS)
App Features: Buzzer, Push Notifications, Map
Alert Modes: Device buzzes + Phone buzzes
Use Cases: Keys, Wallet, Bag, Any Daily Essential
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About the Client & Product
The client approached Stealth Technocrats with a product concept rooted in a universal everyday frustration: leaving the house without something important. Keys, wallet, ID card, bag — most people have a small set of essentials they need every single day, and most people have experienced the disruption of realising too late that one of those items was left behind.
Phido is a BLE (Bluetooth Low Energy) proximity alert device that attaches to any everyday object. Paired with a React Native companion app on Android or iOS, Phido creates a bidirectional alert zone around the user and their tagged items — buzzing the device if the phone walks away, and buzzing the phone if the device walks away. If the connection drops for any reason, both alert simultaneously.
How Phido Works
Phido operates on a simple but powerful principle: as long as your phone and your tagged items are within BLE range of each other (typically 15–20 metres), everything is fine. The moment that range is broken — in either direction — the relevant buzzer fires.
How Phido Works — Scenario by Scenario
| You Leave Without an Item | You attach a Phido device to your keys, wallet, or bag and pair it with your phone. When you walk out of the 15–20 metre BLE range without that item, the device buzzes — alerting you immediately before you get too far. |
| You Leave Without Your Phone | If you pick up all your tagged items but forget your phone, the phone buzzes — giving you an alert from the device side, ensuring the protection works both ways regardless of which item you left behind. |
| Connection is Lost | If the BLE connection drops for any reason — phone battery, signal interference, or moving out of range — both the device and the phone buzz simultaneously so neither end is left silently disconnected. |
| Multiple Devices, One Phone | A single phone can be paired with multiple Phido devices — one on keys, one on a wallet, one on a bag — and each operates independently. Walk away without any one of them and that specific device will alert you. |
The Problem
Despite being a universal experience, the “I forgot something” problem had no truly effective real-time solution. Existing approaches either required active user effort or only worked after the item was already lost. Six specific challenges defined what needed to be built:
Core Problems Addressed
| The "Did I Forget Something?" Problem | Most people have a handful of items they must carry every day — keys, wallet, phone, bag, ID card. Forgetting even one causes significant disruption. There was no passive, automatic way to ensure all essentials were with you when you left. |
| One-Sided Tracking Solutions | Existing solutions like GPS trackers or simple Bluetooth finders were one-directional — you could find a lost item on a map, but the item could not alert you in real time as you were walking away from it. By the time you checked the app, you were already far from home. |
| No Bidirectional Alert System | No consumer device provided true bidirectional proximity alerts — where both the item AND the phone would buzz when separated. This asymmetry meant if you forgot your phone but had everything else, you'd have no way to know from the device side. |
| Complex Hardware-Software Integration | Building a reliable BLE device requires tight coordination between firmware (the hardware buzzer logic), the BLE advertising protocol, and the mobile app (connection management, RSSI thresholding, notification delivery). This cross-disciplinary challenge is beyond most standard app development teams. |
| Unreliable BLE Connection Handling | BLE connections drop frequently due to device movement, battery fluctuation, and radio interference. Without robust reconnection logic and drop-detection, a product that silently loses connection without alerting the user is worse than no product at all. |
| Cross-Platform App on a Single Codebase | Delivering a reliable BLE-connected app on both Android and iOS is non-trivial — each platform handles Bluetooth permissions, background processes, and BLE scanning differently. Building and maintaining two separate native apps would double the cost and complexity. |
The Solution
Stealth Technocrats engineered Phido as a tightly integrated hardware-software product — a custom BLE device working in lockstep with a React Native app — where every design decision was made to maximise reliability and minimise the friction of daily use:
Technology Architecture
| BLE Device (Phido) | Physical device with BLE chipset and onboard buzzer — attaches to any everyday item; broadcasts BLE signal continuously within 15-20m range | |
| BLE Protocol Layer | Handles BLE advertising, connection establishment, RSSI signal strength monitoring, and disconnection detection between device and phone | |
| React Native App | Single codebase for Android and iOS — manages all paired Phido devices, monitors connection state in foreground and background, and triggers alerts | |
| Bidirectional Alert Logic | Custom alert engine: device buzzer fires when phone exits range; phone buzzes (app notification) when device exits range; both buzz on connection loss | |
| Last Known Location (Map) | When a device goes out of range, the app logs and displays its last known GPS location on a map — giving users a starting point to find a left-behind item | |
| Push Notifications | Background-aware notification system alerts the user even when the app is not in the foreground — no need to keep the screen on for proximity alerts to fire |
Alert Logic — All Scenarios Covered
The bidirectional alert system is designed to handle every proximity scenario with no silent failures:
| Scenario | Device Buzzes | Phone Buzzes | Map Updated |
|---|---|---|---|
| Walk away without tagged item | Yes | No | Last location logged |
| Forget phone, carry item | No | Yes | Not applicable |
| BLE connection lost (any cause) | Yes | Yes | Last location logged |
| Item back in range | No | No | Alert dismissed |
Features Delivered
Six core features were engineered across the BLE device firmware and the React Native companion app:
Features Delivered
| Bidirectional BLE Proximity Alert | The defining feature of Phido — both directions are monitored simultaneously. When the phone moves out of the device's BLE range, the device buzzer fires. When the device moves out of the phone's range, the phone triggers an alert. This ensures the user is notified regardless of which item was left behind. |
| Multi-Device Pairing | A single Phido app can be paired with multiple Phido devices at the same time — one on keys, one on a wallet, one on a bag, one on a laptop. Each device operates and alerts independently, so leaving behind any single item triggers only that device's alert without affecting the others. |
| Connection Loss Detection | The app continuously monitors the BLE signal strength (RSSI) of all paired devices. If the connection drops — due to range, battery, or interference — both the device and phone buzz simultaneously. This prevents silent disconnections that would otherwise give users false confidence. |
| Last Known Location on Map | When a Phido device goes out of BLE range, the app captures and stores the phone's last GPS coordinates at the moment of disconnection. These are displayed on a map in the app, giving users a concrete starting point to retrace their steps and recover a forgotten item. |
| Background Push Notifications | The app operates reliably in the background on both Android and iOS. When a proximity alert is triggered and the user's screen is off or they are using another app, a push notification fires immediately — ensuring alerts are never missed due to app state. |
| React Native Cross-Platform App | A single React Native codebase delivers a consistent, fully-featured companion app on both Android and iOS. The app handles all BLE scanning, connection management, device registration, alert configuration, and map display — with platform-specific BLE permission handling abstracted cleanly beneath the shared codebase. |
The Results
Phido delivered a complete hardware-software product that solves a genuine, daily-life problem in a way no purely software solution could. The combination of a physical BLE device and a cross-platform React Native app created a seamless, always-on proximity safety net for everyday essentials:
1
Platforms
Android & iOS — single React Native codebase
What Phido eliminated and what it enabled:
Customer Reviews of the Case
Giles and his team at Safebyte Business Consulting have been absolutely great to work with and they definitely have gone above and beyond for us by streamlining all of our accounts so that we can focus on what we do love to do and continue to grow our business.
Safebyte is an excellent platform for anyone interested in IT. The website offers a wide range of articles, tutorials, and guides that cater to both beginners and advanced users. The content is well-organized, easy to understand, and always up-to-date with the latest trends in technology.
