Live Blockchain Demo
3. Block
A block wraps data with a block number and a nonce, and hashes all three together. The network only accepts blocks whose hash starts with four zeros — so when you change the data, the block breaks (turns red). Press Mine to search for a new nonce that makes it valid again.
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This interactive demo was created by Anders Brownworth and is rebuilt here as a self-hosted, dependency-free version. SHA-256 runs entirely in your browser; blocks turn red when their hash no longer starts with 0000 and green again once re-mined.