CallShields listens in the background and alerts you the moment a call shows scam signals — privately processed on your device or secured in the cloud.
"Bank account" + "urgent verification" pattern detected.
CallShields works silently in the background — no setup required after installation.
CallShields runs in the background using Android's Accessibility Service to capture call audio.
Vosk converts speech to text entirely on your device — no audio ever leaves your phone.
The transcript is analyzed by an LLM to score scam probability, flag red flags, and recommend action.
We built CallShields with the belief that privacy isn't a feature — it's a right. Every architectural decision reflects that commitment.
View Source on GitHubEverything stays on your device. Vosk transcribes audio offline. Zero data sent to any server.
Only anonymized text transcripts are sent — never audio. Secured with Supabase RLS and JWT auth.
Our full source code is on GitHub. Audit every line. Trust through transparency, not promises.
Phone fraud costs billions annually. The elderly and vulnerable are hardest hit — often targeted by sophisticated social engineering that plays on fear and urgency.
Existing solutions require cloud audio uploads or charge expensive monthly fees. We wanted something anyone can use, privately, without surrendering their data.
CallShields is built by developers who believe in open, trustworthy tools. Our local mode is free forever — because everyone deserves protection.
We offer two modes to fit your needs and privacy preferences.
Local & Private
Just by downloading our app—no sign up required—you can enjoy local model support. All processing happens completely on your device, works without internet, and stays 100% private.
Enhanced Protection · $14.80/month
For users at higher risk of targeted scams. Scammers often use personalized tactics and your personal information to seem credible. Our paid plan uses state-of-the-art language models to detect these nuanced attacks—notifying you seconds before you fall into their trap.
Join thousands of residents who trust CallShields to protect them from fraudulent calls — privately, accurately, and for free.