Private AI · In preview

Every prompt is a disclosure.

Consumer AI moves client matters into someone else’s infrastructure — their monitoring, their retention rules, their jurisdiction. Letro Private AI works in an isolated environment assigned to your organisation. Never used for training. Never shared with model providers.

Device
Letro app
Your organisation’s AI environment Letro-operated · Europe
Inference
Self-hosted Mistral models
Outside your boundary
Model provider✕
Never receives your data
Promptstays inside the boundary, end to end
Messaging at restSwitzerland

01 · This is not speculation

Three public facts about cloud AI.

Each one is documented, and none of them is a scandal. They describe how consumer AI services work.

Providers can see what flows through them.

On 10 September 2026, Anthropic published its fourth threat-intelligence report: eight months of platform misuse it identified, reviewed and disrupted. This monitoring is legitimate and necessary. It also means everything entering a consumer AI service sits inside the provider's compliance perimeter, not yours.

Source: Anthropic, September 2026

Retention is not yours to control.

In 2025, a US federal court ordered OpenAI to preserve user conversations, including chats users had deleted, as evidence in litigation. The order was later lifted. What a provider keeps, and for how long, is decided by the provider and the courts it answers to.

Source: OpenAI, June 2025

The leak is usually an employee, not an attacker.

In 2023, Samsung restricted staff use of generative AI after engineers pasted confidential source code into ChatGPT. No breach was needed: a convenient tool and a deadline were enough.

Source: Bloomberg, May 2023

None of these are scandals. They are the architecture of cloud AI: if a provider can write a threat-intelligence report, it can read what flows through it.

02 · What Private AI is

One assistant for your work and your clients

It runs inside your Letro environment, bound to verified PostNumber identities. Nothing leaves your boundary.

Review documents

Summarise a mandate, compare versions, extract obligations and deadlines.

Design workflows

Turn a recurring approval chain into one structured, repeatable process.

Draft and communicate

Prepare correspondence in your register, addressed to verified counterparties.

Animation: in the Letro app, a Private AI tab appears next to Desk. A workflow is described in plain words: check each client instruction against the mandate; over CHF 50,000, Compliance and the relationship manager both approve; then confirm to the client. Private AI drafts six steps and the workflow is switched on. Results shows a new instruction awaiting approval, and History opens a past run with its full audit trail. Approvals always stay with a person. Illustrative example with fictional names.

Guarantee 01
Never used to train any model

Not ours, not anyone’s — on any tier.

Guarantee 02
Never sent to a model provider

Letro operates the models itself, on dedicated compute.

03 · How it works

Four steps. One boundary.

Your workspace
Document
AI environment · Letro-operated · Europe Self-hosted Mistral models. No model provider can reach it.
Letro Private AI
01

Share a prompt or document

02

Encrypted in transit

03

Processed only inside

04

Result returns · no training

Cloud
Organisation-scoped
Dedicated
Fully isolated
Sovereign
Not offered yet

Messaging data at rest remains in Switzerland (Infomaniak). AI processing runs on European infrastructure, outside the Swiss messaging environment.

04 · What we don’t claim

Claims you can check. Nothing else.

A page about confidentiality should be as careful with its language as with your data. Two things we deliberately do not say.

We don’t sell “sovereign AI” we can’t deliver

On-premise inference needs GPU infrastructure few firms can justify. We offer Private AI only where we guarantee the isolation ourselves — dedicated, Letro-operated European environments.

We don’t claim to beat the largest consumer models

Private AI is built for document review, drafting and workflow. There, the binding constraint is confidentiality, not benchmark scores.

Browse the security questions we answer in full — architecture, key custody, data residency and subprocessors. The published Matrix audits cover the protocol Letro is built on; an independent penetration test of Letro itself, by ImmuniWeb, is underway (September 2026).

Visit the Trust Center

External asset managers · Law firms · Trustees and fiduciaries · Family offices

Professionals whose correspondence carries legal weight, and whose duty of confidentiality does not pause when the tool is convenient.

05 · Diligence

The questions your due diligence will ask.

Where is my data processed?

Messaging data is stored in Switzerland (Infomaniak). Private AI processing runs in Letro-operated environments on dedicated European infrastructure, scoped to your organisation. Nothing is processed by a model provider.

Can Letro read the content of my messages?

No. Message content and attachments are end-to-end encrypted (Matrix Olm/Megolm); the server stores ciphertext.

Then what does Private AI see?

What you choose to share with it, and nothing else. Your prompt travels encrypted from your device to the AI environment assigned to your organisation, and is decrypted only inside that isolated environment, at the moment of processing. It is not retained for training, and no model provider can reach the environment.

Is my data used for training?

No. Never, on any tier.

Which companies are involved in running Private AI?

The models are Mistral's, deployed and operated by Letro. Mistral itself has no access to your data. During preview we don't publish infrastructure partner names, because the setup is still evolving; we walk through the full architecture in demos.

What does early access cost?

Private AI preview is included for early-access participants. Standard founding terms apply platform-wide: first 3 months free on every tier, and a 30-day free trial. Apply as a founding firm →

06 · Early access

Get early access to Private AI.

Tell us where you'd run it. We onboard in small groups, by tier.

Prefer to see it first?

Book a demo →
Where would you want it to run?
Thank you. You're on the early-access list.We onboard in small groups, by tier, and will be in touch from a Letro address. Want to see it now? Book 20 minutes with us →
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