Designed for Security. Trusted by Teams.
From AES-256 encryption to zero-knowledge storage, AtumSeal keeps your sensitive messages truly private.
Secure by Design
Every note is encrypted end-to-end with AES-256 and stored with zero-knowledge architecture. Only the intended recipient can unlock it — nobody else.
Simple, Fast, No Accounts
Send a secure, self-destructing note in seconds. No login, no setup - just a safe, one-time message with total privacy.
Built for Professionals
Tailored for MSSPs and cybersecurity teams to exchange confidential information securely - simple, trusted, and hassle-free.
One Click. One Breach.
Nearly 1 in 6 cyber intrusions still begin with phishing.
Why Teams Choose AtumSeal
Standard email is inherently insecure. Once sent, sensitive information lives in inboxes indefinitely — accessible to admins, exposed in breaches, and forwarded without your control. AtumSeal eliminates the risk by ensuring your message exists only long enough to be read once, then disappears permanently.
Trusted by MSSP teams, Private Equity firms, and legal professionals, AtumSeal is purpose-built for the moments when confidentiality isn't optional: sharing credentials, API keys, NDA-sensitive terms, or any information that shouldn't persist in an inbox.
Zero-knowledge encryption
Notes are encrypted in your browser before transmission. Our servers never see your content.
Self-destructs on read
The moment your recipient opens the note, it is permanently and irreversibly destroyed.
No account required
Create and send a secure note in under 30 seconds — no login, no friction.
AtumSeal — Frequently Asked Questions
No. Notes are end-to-end encrypted before leaving your browser. AtumSeal's servers never have access to the plaintext content. Only the recipient with the unique link can decrypt and read the note.
The note is permanently and irreversibly destroyed after the first read. There is no copy stored on our servers, no archive, and no way to retrieve it.
You set the expiry when creating the note. Options include destruction on first read, or automatic expiry after a set time period (e.g., 24 hours, 7 days).
No. AtumSeal requires zero login or registration. Create and share a secure note in under 30 seconds.
AtumSeal is used by security teams, executives, and legal professionals to share passwords, API keys, NDA-sensitive documents, confidential HR communications, and financial data.
Yes. Completely free to use. No credit card, no account, no limits on note creation.
Insights & Solutions That Protect What Matters
Explore expert whitepapers and discover tools like AtumSeal that keep your sensitive data safe.
Is Your
Domain
Being
Spoofed
Securely?
Email attackers often impersonate your brand — check your domain in seconds.
Spoofing Update
Six months after revealing that most mid-market private equity (PE) firms and their portfolio companies were vulnerable to email domain spoofing, Atumcell took another look. Despite scattered improvement, the threat remains pervasive.
Web App Penetration Testing
Portfolio companies are rapidly adopting web apps, which create serious security risks. These apps require penetration testing to mitigate risks for portfolio companies, customers, and investors.
Driving Portfolio-wide Value with Cybersecurity
Private equity firms can achieve a high ROI on cybersecurity spending. To do so they need a pragmatic, measurable, and sustained approached. This five-step roadmap shows the way.
Domain Spoofing: A Widespread Risk at PE Firms & Portfolio Companies
55 percent of mid-market PE firms and portfolio companies are vulnerable to domain spoofing, which enables phishing. No firm is fully protected across its portfolio. We've ranked the top 20 firms based on their level of protection.
A Pragmatic Guide to OT Cybersecurity in 2025
Beginning an Operational Technology (OT) cyber security journey can feel overwhelming. This guide lays out a straightforward roadmap to help make tangible progress in a reasonable timeframe.
Losing Ford Millions, With Just Four Lines Of Code
An Atumcell Red Team developed and deployed a rogue micro-controller to demonstrate Ford's vulnerability to cyber/physical attack