Bitcoin Hash-Based Giveaway System
Paste the entry list and draw with a result nobody can rig — not you, not us. The winner comes from the hash of a Bitcoin block, and anyone can check it.
- Free
- No sign-up
- Result from a Bitcoin block
- Link and result by email
- Page to share
When you click Draw, the list is frozen and recorded on Bitcoin, and the result comes from the next block (about 20 to 30 minutes). You get a link to follow and share.
The giveaway page is public to anyone with the link (the list of names is shown). Don’t paste personal data beyond names.
How it works
Paste the list
Names, @usernames or numbers, one per line. Up to 5,000.
Bitcoin decides
The list is frozen and the winner comes from the hash of a block that didn’t exist yet.
Anyone can check
The page shows the math and downloads the proof to check on opentimestamps.org.
Check the result with the .ots file
Already run a giveaway here? Upload the .ots file you downloaded: we find the giveaway, check the record on Bitcoin and show which block and date the list was recorded in.
The check redoes the math from the file up to the Bitcoin block header — the same check as the official OpenTimestamps client.
Why the Bitcoin hash?
In an ordinary giveaway, whoever presses the button could repeat it until the name they want comes up. Here that’s impossible: the list is frozen first, and the winner comes from the hash of a Bitcoin block that didn’t exist yet when the list was closed.
A block’s hash is unpredictable and public — thousands of computers around the world compete to create it. Nobody, not even Anyza, can choose the result, and anyone can redo the math and arrive at the same winner.
See in detail how the giveaway works →The math, the same for everyone:
sha256(“block hash:giveaway id:k”) → first 15 hex characters → remainder of division by N
Frequently asked questions
What is a giveaway based on the Bitcoin hash?
It’s a giveaway where the winner is calculated from the hash (the “fingerprint”) of a Bitcoin block mined after the list was frozen. Since nobody knows that hash in advance, nobody can manipulate the result.
How do I know the giveaway wasn’t rigged?
The list is frozen and recorded on Bitcoin (OpenTimestamps) before the block that decides is mined. On the result page, the check button redoes the math in your browser; you can also download the list and the proof and check them at opentimestamps.org.
How long does the result take?
Usually 20 to 30 minutes — the time for the chosen block to come out plus one on top, to confirm. The page shows a countdown and refreshes on its own.
Can participants check it?
Yes. Share the link: anyone can see the frozen list, the block used and the winners, and can redo the math. It’s the most transparent way to run a giveaway on Instagram, WhatsApp or a livestream.
What is the email for?
To send you the giveaway link right away and the result when the block comes out. The email doesn’t appear on the page and isn’t used for advertising.
How much does it cost?
Nothing. The giveaway is free, with no sign-up, for up to 5,000 participants and up to 50 winners.
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