Citadel Dispatch CD184: CALLE - BITCHAT AND CASHU
Nov 24, 2025
Calle, the creator behind the Cashu open-source protocol and maintainer of BitChat Android, dives into the fascinating world of privacy and offline communication. He discusses the explosive growth of BitChat during protests and outages, revealing how download spikes can foreshadow unrest. Calle also compares Bluetooth mesh technology with Nostr integration, explores ephemeral identities, and highlights Cashu's rapid development in the Bitcoin ecosystem. He emphasizes the need for more Bitcoin developers and invites listeners to contribute to the thriving community.
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Organic Growth From Real-World Need
- BitChat grew organically to ~900k Android downloads without formal marketing.
- Calle observed adoption driven by users who recognized mesh value during outages and protests.
Downloads Predict Local Unrest
- BitChat saw download spikes in Nepal, Indonesia, Madagascar, Côte d’Ivoire and Jamaica tied to protests and a hurricane.
- Calle used store-console spikes to discover unrest before news often reached him.
Deterministic Geohash Relay Selection
- BitChat uses a geohash-driven relay selection to decentralize Nostr usage and avoid user relay choices.
- The app deterministically picks closest relays from a 300-relay list so chat participants share at least one relay.
