Keep your email. Add a layer of privacy.

Seal what you would rather Google did not read. Your words and files are sealed on your device; the email carries a link. The person who opens it needs no account, no app and no password.

Open a sealed message Send one yourself

That first button opens a real sealed message from the pup, the way your client would see one. Free to try. Nothing to install, on either side.

Sealed message Nothing is fetched until you tap. It opens here, in your browser, and nothing is installed. Open message From James, at Lisbon Property Your passport scan and the signed page are attached. Nothing else needed from you until Friday. passport.pdf · 2 MB Reply sealed

Sending a client's bank details at four o'clock? Seal it.

  • A passport scan for a letting agent or a conveyancer.
  • Bank details for a refund, a deposit, a payroll change.
  • A medical result or a therapist's notes.
  • A contract before it is signed, or the signed page after.
  • A password for a colleague who is locked out.
  • Anything you would not pin to a noticeboard.

All of it goes through a mail server that reads every line, indexes it, and keeps it for years. Privacy is not about having something to hide. It is about deciding who reads your words, and the answer for most of them should not be a company you have never met.

Seal Pup lets you keep the email you have and take that decision back, one message at a time. The person at the other end taps a link and reads. That is the whole of their side.

How it works

  1. 1

    Write it in Seal Pup

    Your words and any files, up to 1 GB. They are sealed on your device under a key made for that one message.

  2. 2

    The email carries a link

    Send it from your own address, let Seal Pup send it for you, or copy the link into a text or a chat. The email holds the link and nothing else.

  3. 3

    They tap, and read

    The link opens in their browser. One tap shows the words and files. No account, no app, no password to make up. They can reply sealed from the same page.

The key to the message travels after the # in the link, the part of a web address a browser never sends to any server. So the store holds bytes it cannot read, the email carries a link it cannot open, and only the person with the link can read the message. The Privacy page says exactly what we can and cannot see.

What it does, and what it does not

It does

  • Keep the words and files out of your mail server, and out of theirs.
  • Let you take a message back. Unsend deletes it, and the link stops working.
  • Add a passphrase for the few that warrant it: three plain words you tell them by phone.
  • Bring replies back to you sealed, with files, on the same page they opened.

It does not

  • Hide that an email was sent, or to whom. Mail servers still see the envelope.
  • Stop a person who holds the link from opening it. The link is the key; a passphrase is the answer when that matters.
  • Hide the subject line, so Seal Pup writes a plain one for you.
  • Replace your email. It sits beside it.

Built on the same sealing engine as BITS, where it has carried people's private notes, mail and messages since 2026. Every message is sealed with the browser's own cryptography; nothing of ours sits between your device and the store but a file name.

"I'm the seal who runs this place. I keep the store, I count the passphrase misses, and I cannot read a word of what you send. That is not a policy. It is how the thing is built. If I could read it, you would have no reason to use it."

The pup

Made for people who send sensitive things for a living

Accountants and bookkeepers. Solicitors and conveyancers. Advisers and brokers. Clinics and therapists. Recruiters, letting agents, anyone with a data-protection duty and a client who has never installed anything. The client's side is a web page and one tap, which is the whole point.

Free while Seal Pup is new. Firms will pay a monthly price later, and anything you seal now stays sealed.

Start sending sealed