Write a note to the future. It's encrypted right here in your browser and sealed into a single capsule file — open that file any time and it shows a live countdown; on the day you chose, it opens. No account, no server, works offline for decades.
Some messages are better with a delay. A letter to yourself to open in ten years. A note for your kid's 18th birthday, written while they're still asking you to check for monsters. Predictions sealed on New Year's Eve. A message to your spouse for a milestone anniversary. This tool turns any of them into a capsule: a single, self-contained file that shows a sealed envelope and a live countdown whenever it's opened — and then, on the date you chose, opens itself and reveals the note.
.html file containing the sealed ciphertext and its own opener. Store it, email it to yourself, give it as a gift, drop it in cloud storage. It needs no app and no internet, so it will still open in a browser many years from now.Here's the truth most "time lock" tools won't spell out: a file that opens itself offline must carry its own key, and pure mathematics has no concept of a calendar. So Time Capsule Notes gives you two different locks and is explicit about what each one guarantees:
For a gift capsule, a nice pattern: seal it with a passphrase, and give the passphrase to someone you trust to hand over on the day.
The capsule deliberately uses nothing but plain HTML and the Web Crypto API built into every modern browser — no libraries, no fonts to fetch, no links back to us. If The Dollar Web disappeared tomorrow, every capsule ever made would keep working. Keep a copy anywhere you keep files you care about; it's a few kilobytes.
Write the note, pick the open date, and download the capsule: a single self-contained file showing a live countdown that will not reveal the contents until the day arrives. Store it wherever you keep things that matter.
The text is encrypted with AES-256 in your browser and sealed inside the capsule file, which checks the date before decrypting. No tricks with hidden text: before the date, the contents are cryptographically unreadable.
Websites shut down, and your 2036 letter goes with them. A self-contained file has no service behind it: as long as you keep the file, the capsule works, which is the only durability model worth trusting for decades.
Letters to yourself in five years, notes for a child's eighteenth birthday, wedding-day letters to open on anniversaries, and predictions sealed for the reunion.
No. Writing, encryption, and sealing all happen in your browser; the only copy of the capsule is the file you download.