SafeSMS: On-Device Threat Detection with Gemma 4 E4B, no internet required

This is a submission for the Gemma 4 Challenge: Build with Gemma 4 SafeSMS is a privacy-first Android application designed to protect users from the rising threat of SMS-based scams, phishing, and spam. Traditional SMS scanners and spam filters often send your private text messages to the cloud for analysis, creating severe privacy concerns. SafeSMS takes a completely different approach: it brings the intelligence directly to the device. By running a powerful, on-device AI model, it performs real-time threat detection locally on your phone. It monitors incoming messages, categorizes them (SAFE, SUSPICIOUS, or SCAM), provides a confidence score, and explains why a message is dangerous. The app features a sleek dark-mode UI built with Jetpack Compose, including: Incoming SMS: Your bank account will be blocked. Click immediately: http://bit.ly/xyz SafeSMS Output: [https://youtu.be/2NhvyiARX1c] To enable real-time, completely private SMS analysis, SafeSMS uses Gemma 4 via LiteRT for on-device inference. I selected the E4B model because it perfectly fits mobile and edge environments: Absolute Privacy All SMS data stays on-device. No cloud calls, no data leakage. Zero Latency & Offline Capability Messages are analyzed instantly without any network dependency. Resource Efficiency The lightweight model runs efficiently inside a background Android service with minimal battery impact. Strong Reasoning in a Small Model Despite its compact size, the model effectively detects: The model is prompted using a structured classification + reasoning format, enabling it to return: This ensures both accuracy and transparency in predictions. SafeSMS follows a fully on-device architecture, ensuring privacy, speed, and reliability. Incoming SMS Protection Service SafeSMS Model Controller On-Device AI Inference Result Handling User Interface (Jetpack Compose) SafeSMS demonstrates how powerful AI models like Gemma 4 can run entirely on-device, enabling real-world applications that are fast, private, and reliable. It’s a step toward a future where user data never has to leave their device to stay safe.