30+ detection layers with an on-device ML model | 51,407 spam numbers | Real-time caller ID | RCS filter | No API keys

CallShield blocks spam calls and flags spam texts with an on-device engine of more than 30 detection layers. They include a gradient-boosted tree ML scorer, bounded campaign and churn evidence, conservative carrier identity signals, an RCS notification filter and real-time caller ID. Its 51,407-number database sits alongside a trending-numbers feed the app checks every 30 minutes. There are no accounts and no tracking.

The database keeps data/spam_numbers.json as a stable legacy GitHub-raw endpoint for older clients, while current builds bundle a hash manifest and 256 content-addressed shards. The manifest, the legacy database, the trending feeds and the model weights each carry a detached ECDSA P-256 signature, and the app refuses any of them that doesn’t verify against a key built into it. Devices fetch only changed shards, check every shard against the signed manifest before a transactional Room refresh, and fall back to the legacy snapshot when the shard service is unavailable.

Screenshots

Getting Started

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