Swiss · encrypted · evidential

Sent isn’t proof.

Communication your firm can stand behind — built for regulated work.

Book a demo See pricing

Apps for iPhone, iPad, Android and web · from CHF 12 per seat

Wavestone
Swiss Cybersecurity Startup Radar 2026
Category: Secure Data Exchange →
Swiss Startup Association
Founder interview
Sina Tadayon, founder of Letro Tech →
Least Authority
Audited cryptography
vodozemac (Matrix), 2022 · read the report →
ImmuniWeb
Independent penetration test
September 2026 · in progress →
The problem

Ordinary channels can’t carry regulated work

You already know this. The client texted the payment change. The mandate went by email. The proof was never a system — it was someone’s memory.

Billions

in off-channel fines

WhatsApp and personal email have cost regulated firms billions in penalties. The message was fine. The record didn’t exist.

Anyone

can be your client

Email has no verified sender. One character in a domain is the whole of payment fraud, and AI now writes the message for them.

10 years

later, prove it

A regulator asks what was sent, to whom, and when. Screenshots are not evidence. A mailbox export is not proof.

30-second self-audit

Four questions. Answer honestly.

Tick what happened in your firm this month. Nobody sees the result but you.

0/4

Consumer messengers hide everything. Office tools prove nothing.
Regulated work needs privacy and proof.

The platform

One platform, four parts

Each part does one job. Together they make an exchange that survives the audit.

01

Evidential platform

Chat, files and rooms that log themselves. Secure, evidential communication for regulated client work.

02
14:02:07

LetroLetters

Formal correspondence with a timestamped, tamper-evident record. Registered post, without the post.

03
UK32567

PostNumber

One verified identity per person, issued after passport verification. No anonymous counterparties.

04

Organisations

Hierarchies, roles and approval workflows built in. Governance sits around the message, never inside it.

Letro Private AI
In preview

Your client files should not become someone’s training data

Private AI reads the documents, drafts the correspondence and structures the workflow inside an isolated, Letro-operated European environment assigned to your organisation. Nothing leaves it to a third party. Nothing trains a public model.

Review a 60-page mandate and surface what changed
Draft the reply in your house language, ready for approval
Works inside the same encrypted channel as the rest of the matter
Letro-operated · EU · isolated
Mandate v4.pdf
Notice period · 60 days
Governing law · CH
Fee schedule changed
Approval block missing
No route out
Public model providersNever receive your content
Governance and access

Security does not stop at encryption

Encryption protects the content. Governance decides who may send it, who signs it off, and what happens when someone escalates.

01

Organisation-aware structure

Model communication around departments, legal entities, teams and external counterparts.

02

Role-based access control

Define who can view, send, approve, escalate or administer communications.

03

Approval and escalation

Review steps, escalation paths and audit-friendly process design.

04

Built on Matrix

An open standard for decentralised communication: homeservers talk directly, so separate firms stay on separate servers. Federation is opt-in per deployment. Air-gapped deployment where assurance demands it.

Visit the Trust Center →
External participants

Your clients don’t need Letro

Reach anyone by email — they get a link to a temporary room, free, no account required. Your clients see the professionalism. You keep the record.

Works for counterparties, co-trustees and one-off contacts: no account and no onboarding on their side.

YouPostNumber verified
Email invite
Your clientTemporary room · free
50 years of client communication

Post, email, messaging — then Letro

1970s

Post

SlowManual trackingLimited reachSecurity by envelope
1990s

Email

Fast, insecure by defaultNo verified senderPhishing lives hereNo reliable audit trail
2010s

Messaging apps

InstantCasualNo formalityDetached from the firm
Today

Letro

Verified senderEncrypted contentDelivery you can proveBuilt for organisations
Deployment

Choose your level of control

Run Letro on shared Swiss infrastructure, on a dedicated homeserver, or entirely inside your own perimeter.

Cloud

Shared infrastructure hosted in Switzerland. No setup fee, 10-year retention included.

Dedicated

Your own isolated homeserver on Swiss infrastructure, run and maintained by Letro. Separation without operating anything.

Sovereign

Runs inside your own data centre or private cloud, up to fully air-gapped. Your servers, your perimeter, your control.

Founding offer · first 3 months freeSee transparent pricing

See Letro on your own cases in 30 minutes

Bring a real client scenario. We’ll show you the encrypted exchange and the evidential record it leaves behind.

Book a demo Join as founding firm