Write to someone across the years. A child at eighteen, yourself at sixty, a stranger in 2126. Seal it as a folder and a few printed pages. Keep it in a drawer.
How it works ↓The machine below is real. Watch it write, then it's your turn.
A letter is sealed with a date, a keeper, and a token broken in two. Nothing here leaves your device.
The letter comes first. The desk is above.
“Your mother” can outlive a name. Sign it the way you want to be met.
A custodian keeps the sealed letter safe and passes it on with its story. You can simply keep it yourself.
A passphrase locks the letter file against strangers. It does not enforce the date, and most letters should not have one, because a lost passphrase is a lost letter. Read the honest part first.
For · opens . The folder has downloaded: the letter, its manifest, a README for whoever finds it, and this token to cut in two.
Three verbs, no cloud.
A quiet page that works offline, on this device. No account, no server; nothing leaves your machine.
Sealing makes a folder of plain files and a print kit. Paper is the reference copy; the folder is its shadow.
One half of the token stays with you; the other travels with the letter. Decades later, the halves must meet.
Tessera cannot stop anyone opening a letter early, and will not pretend it can. Sealing here is ritual and custody, not enforcement. There are no delivery promises, because there is no deliverer.
What holds instead: a named keeper, a printed date, and the small ceremony of a token broken in two. The way it has always worked.
A passphrase, if you use one, locks the letter’s words against a stranger who opens the box too early. It is privacy, not a clock. It cannot hold the date shut, only keep the words unreadable without the key. That is the honest limit, and Tessera will not dress it up as more.
So the key lives on paper. When you lock a letter you can print a key card and give it to someone who is not the keeper, so that opening it takes two people meeting, not a server that has to still be running in forty years.
Most letters are better left open. A passphrase no one remembers is a letter no one can read, and the people likeliest to lose it are the very heirs you were writing to. Lock a letter only when a stranger reading it early would truly harm someone.
Your letters never leave this device. There is no account and no analytics of any kind.
In the ancient world, hosts and guests broke a piece of clay or bone in two and each kept a half, so that even their descendants, strangers to each other, could reunite the halves and be recognised.
Every sealed letter mints one. The broken edge is the signature; no two break alike. Cut it in two: one half stays in your drawer, the other travels with the letter until its day.
One half stays with you. The other travels with the letter.
The ledger of what this house is keeping.
Nothing is waiting yet. The desk above writes the first one; sealed letters take their place here.
Letters sealed at the desk above join the shelf. Stored on this device only.