How it works

Sealed Posts is a place to put something on the record: a prediction, a promise, or anything you want to prove you said first. Posts can never be edited, and anyone can check that.

Two kinds of posts

• Sealed: the text stays hidden until a date you choose, from one hour to ten years away. An optional headline is visible right away, so people know what’s coming.
• Public: visible now, and locked forever.

Either kind can be listed (shown in feeds and on your profile) or a private link that only people you share it with can open. A private post can never become listed later. That way nobody can quietly make 20 predictions and publish only the ones that came true.

The proof

When you post, we combine your text with the post’s details and a random secret (the nonce), then compute a SHA-256 fingerprint of the result. Change one character and the fingerprint is completely different.

1. The fingerprint is shown on the post right away, even while the text is sealed.
2. Within seconds it’s sent to OpenTimestamps, which records it in the Bitcoin blockchain, usually within a few hours. After that, not even we could backdate or swap it.
3. When the post opens, the full text and nonce are published. Anyone can recompute the fingerprint and see it matches the one shown from day one.

The nonce is why a short sealed post like “Dodgers” can’t be guessed from its fingerprint: without the secret, there are too many possibilities to try.

You can download each post’s .ots proof file and check it with any OpenTimestamps tool, or paste a post’s text on our verify page.

No edits, no deleting

Authors can’t edit or delete posts. If you delete your account, your posts stay but switch to a random anonymous name. Moderators can hide or remove posts that break the rules. When that happens, a placeholder with the original fingerprint and dates stays in place, so the record stays honest.

Accounts

You can post without an account, under a random name like “Amber Otter 4821.” Sign in with Google to post under your own @handle and build a public track record. Only signed-in people can upvote, and you can upvote a sealed post only after it opens.