For Chiefs of Staff, Founders, GPs & PMs

Your private AI
chief of staff

Six meetings a day. A hundred relationships to maintain. Decisions that can't wait. Cossi gives you a spoken brief every morning — from your own data, running entirely on your device. No cloud. No context leaks.

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People
Relationship pulse
Your network
SM
Sarah Mitchell
3 days ago · Strong
JK
James Kessel
18 days ago · Drifting
TP
Tom Parker
47 days ago · At risk
✦ Nudge
James is in your Q2 planning session today — good moment to reconnect.
📋
Brief
💬
Chat
📅
Calendar
✉️
Mail
⚙️
Settings
Good morning, K.
Monday · 3 meetings · Amber
KA
Day pressure
✦ AI Brief
Moderate day. Q2 planning is the priority — James hasn't seen the budget revision yet. Two drafts awaiting your review.
Q2 Planning — Kessel, Mitchell
09:30 · Zoom · 60 min
▶
Amex Strategic Review
14:00 · In person · 90 min
▶
1:1 with Sarah M.
16:30 · Zoom · 30 min
▶
📋
Brief
💬
Chat
📅
Calendar
✉️
Mail
⚙️
Settings
✦
Cossi
On-device · Private
Draft a note to James — let's reconnect before our session
✦
Hey James — it's been a few weeks. Looking forward to Q2 planning today. Want to grab 10 min beforehand to sync on the budget numbers?
✓ Draft saved for your review
Set a follow-up for next Thursday
✦
Done. Follow-up with James added to Calendar for Thursday 09:00 and linked to your tasks.
Message Cossi…
↑
📋
Brief
💬
Chat
📅
Calendar
✉️
Mail
⚙️
Settings
🔐Post-quantum encryption
📱Runs entirely on-device
🚫Zero telemetry
🔑24-word seed recovery
✅Human-in-the-loop always
Built for

Designed for the people
who run the room.

Cossi is not a general AI tool. It's built for knowledge workers who operate at the intersection of information, relationships, and decisions — and who can't afford to put their context in someone else's cloud.

Chief of Staff
The principal's intelligence layer
Managing a principal's calendar, relationships, and information flow across 50+ stakeholders — while keeping nothing sensitive in a cloud tool.
Cossi gives you a morning brief of everything your principal needs to know. Relationship drift alerts before the meeting where it matters. Draft outreach that waits for human approval.
See how it works for CoS →
Founder / CEO
Context at scale
Context-switching between investors, customers, and team — while keeping 100+ relationships from going cold and decisions from compounding into bottlenecks.
Cossi surfaces who you've neglected in your network and drafts the reconnect message before you've opened email. Open decision tracking so nothing stays unresolved past three weeks.
See how it works for Founders →
Partner / GP
Relationship capital, protected
Managing portfolio relationships, LP communications, and deal flow context across a network of 200+ people — none of which should live in a CRM someone else controls.
Relationship health scores for every contact. Drift alerts before a relationship slips below threshold. Full context on your device — encrypted, post-quantum authenticated, recoverable only by you.
See how it works for Partners →
Senior PM / Consultant
Stakeholder intelligence
Maintaining context across multiple products or clients — with dependencies, decisions, and follow-ups that span weeks and span organisational boundaries.
Open decision tracking, per-meeting audio briefs, and follow-up reminders — all surfaced in a single spoken brief each morning. Client data stays on your device.
What Cossi does

The intelligence layer
knowledge workers need.

Cossi connects your calendar, contacts, email, and decisions — and gives you one clear view of what matters each day. Everything on your device. Nothing on a server.

🌅
Morning Brief
Daily AI briefing synthesising calendar, tasks, relationships, and open decisions. Day pressure score, nudges, and a 90-second spoken read-out.
🎧
Audio Meeting Prep
Tap play on any event. Cossi reads you a structured brief: attendee context, agenda, open interdependencies, and the one thing that matters.
👥
Relationship Pulse
Health scores for every person in your network. Drift alerts before relationships fade. Voice notes that surface automatically in your next meeting brief.
✍️
Draft Outreach
One tap to draft a context-aware message for any contact. Sits in a review queue — nothing sends until you approve it.
📬
SMTP/IMAP Email
Connects directly to your inbox via standard protocols. Drafts emails, summarises threads, and surfaces what needs a response. Credentials stay on your device.
🔒
Encrypted Vault
AES-256-GCM encrypted notes and context, signed with ML-DSA-65 (Dilithium). Recoverable via your 24-word BIP-39 seed phrase. No server required.
Daily Brief

Start every day already ahead.

Cossi reads your calendar, cross-references your relationships, and surfaces conflicts and nudges before your first meeting. No setup wizard. No prompting required.

📊

Day pressure score

Green / amber / red signal based on meeting load, overdue tasks, and conflict detection — at a glance.

🔗

Interdependency alerts

Cossi detects when an open decision blocks a meeting, or when a relationship hasn't been touched before an important call.

▶️

Audio meeting briefs

Tap play on any event. A 4-section spoken brief covers context, stakeholders, open threads, and the 80/20 lever.

Good morning, K.
Monday · 3 meetings · Amber
KA
Day pressure
✦ AI Brief
Moderate day. Q2 planning is the priority — James hasn't seen the budget revision. Amex deck is not prepared for the 14:00 session.
Q2 Planning — Kessel, Mitchell
09:30 · Zoom · 60 min
▶
Amex Strategic Review
14:00 · In person · 90 min
▶
⚠ Conflict
Amex deck unfinished. Scheduled tonight conflicts with Tom's call.
📋
Brief
💬
Chat
📅
Calendar
✉️
Mail
⚙️
Settings
Relationship Pulse

Your network, quantified.

Cossi tracks interaction signals — meetings, emails, tasks — and builds a live health score for every person. You see drift before relationships fade.

📈

Relationship health scores

Interaction frequency, recency, and signal diversity combined into a single 0–100% score per contact.

🎙

Voice notes per contact

Record a note about anyone. Cossi transcribes it and surfaces it automatically the next time that person appears in a meeting brief.

📅

Follow-up tracking

Set a reminder and Cossi creates both a task and a calendar event. Pending follow-ups surface in your morning brief.

People
Relationship pulse
Your network
SM
Sarah Mitchell
3 days ago · Strong
JK
James Kessel
18 days ago · Drifting
TP
Tom Parker
47 days ago · At risk
✦ Nudge
James is in your Q2 session today — great moment to reconnect. 18 days since last contact.
📋
Brief
💬
Chat
📅
Calendar
✉️
Mail
⚙️
Settings
A Monday with Cossi

From first alarm to end of day,
never behind.

What a day looks like when your AI chief of staff has already done the preparation work.

6:47am
Morning brief plays while you make coffee
Three meetings today. Two drafts awaiting your review. James Kessel — 18 days without contact — is in your 9:30 Q2 planning session. Cossi flags it before you've touched your phone.
9:15am
Tap play on Q2 Planning
90-second audio brief: James's context, the open budget thread he hasn't seen, and the one thing that needs to land in this meeting. You walk in prepared.
1:45pm
Conflict alert before the Amex review
Cossi flags that the strategy deck is unfinished and that a call you scheduled tonight conflicts with prep time. You reschedule before it becomes a problem.
5:30pm
Draft a reconnect note to Tom Parker
47 days of no contact. You ask Cossi to draft a note. It writes one, in your voice, using context from your last interaction. It waits in the review queue — nothing sends until you approve.
All day
Your calendar, contacts, and emails never left your device
Not by policy. By architecture. There is no server that could have received your data. The AI that powered all of this ran entirely on your iPhone.
vs. the alternatives

Why knowledge workers choose Cossi
over general AI tools.

ChatGPT and Notion AI are powerful. But they require your most sensitive professional data to leave your device. For knowledge workers, that's not a trade worth making.

Capability Cossi ChatGPT / Claude Notion AI
Runs entirely on-device ✓ ✗ ✗
Calendar & email stays local ✓ ✗ ✗
Automated morning brief (no prompting) ✓ ✗ ✗
Relationship health tracking ✓ ✗ ✗
Audio meeting prep briefs ✓ ✗ ✗
Post-quantum authentication ✓ ✗ ✗
Works without internet ✓ ✗ ✗
Human approval before any outbound action ✓ Manual only Manual only
General knowledge & writing Via opt-in API ✓ ✓

* ChatGPT/Claude can be connected via opt-in API key — your key goes phone-to-provider directly, never through Cossi's servers.

Privacy-first by design

Your data stays on
your phone.
Full stop.

Cossi has no server-side user accounts, no analytics pipeline, and no AI model API calls. The AI runs locally on your device. Your contacts, calendar, emails, and vault never leave your hardware.

0
Data points sent to any server
AES-256
Vault encryption standard (GCM)
ML-DSA-65
Post-quantum auth (CRYSTALS-Dilithium)
24
Word BIP-39 seed phrase — your only recovery key
Getting started

Up and running in minutes.

🔑

Create your seed phrase

Generate a 24-word BIP-39 phrase. This is your master key and your recovery mechanism — store it offline. No email. No password. No account.

🧠

Download an on-device model

Choose from the in-app model library. Models run fully offline via llama.rn — no API key, no usage fees, no data sent anywhere.

✦

Your brief is ready

Connect your calendar and email. Cossi begins building your intelligence layer immediately. Your first morning brief is waiting when you wake up.

The AI that works for you.
Not the other way around.

No subscription. No data harvesting. No cloud dependency. Cossi is yours — running on your device, under your key.

Download on the App Store Get it on Google Play
Scan to download Cossi

Scan to download on iPhone