Everything you need to cover Cossi — product description, technical facts, founder bio, and downloadable assets.
Cossi is a private AI Chief of Staff that runs entirely on your iPhone — no cloud, no server.
Cossi gives knowledge workers — Chiefs of Staff, Founders, GPs, and senior PMs — a spoken morning brief, relationship intelligence, and an encrypted vault, all running on-device. Your calendar, contacts, and emails never leave your iPhone, because the AI that processes them does too.
Cossi is a private AI Chief of Staff for knowledge workers, available on iOS and Android. Unlike cloud-based AI tools that require users to upload their calendar, email, and contacts to a remote server, Cossi runs its AI model (llama.rn + DeepSeek R1 1.5B) entirely on the user's device. Each morning, Cossi generates a spoken brief covering the day's meetings, relationship drift alerts, open decisions, and priority tasks — all derived from local data that never leaves the user's hardware. Authentication is post-quantum (ML-DSA-65 / CRYSTALS-Dilithium), and all vault storage is AES-256-GCM encrypted, keyed from a 24-word BIP-39 seed phrase. The core app is free. Pro unlocks Claude and GPT-4 via user-supplied API keys that go phone-to-provider directly, bypassing Cossi's infrastructure entirely.
For publications that want to verify Cossi's privacy claims:
Request assets at press@cossiapp.com — we'll send a download link within 24 hours.
Builder of Cossi. Background in AI systems and mobile engineering. Built Cossi after getting frustrated with AI tools that require you to send your most sensitive professional context — calendar, email, relationships — to servers you don't control.
Available for press interviews and technical deep-dives. Contact: press@cossiapp.com