Merkle Tree

Enter one leaf per line. Leading and trailing whitespace is removed and blank lines are ignored. Up to 16 leaves and 16,384 UTF-16 characters are accepted; longer input is rejected, never truncated. Build runs only when requested. Clear removes the input and result.

This demonstration hashes UTF-8 text: a leaf is SHA-256 of L:text; a parent is SHA-256 of N:left|right, where left and right are the full lowercase hexadecimal hashes. The last leaf is duplicated until the leaf count is a power of two. This is a teaching convention, not the tree format used by Bitcoin or Certificate Transparency. Without Web Crypto, the explicitly labelled FNV-1a fallback is not cryptographically secure.

Change leaf appends ! to the selected text; it does not flip a binary bit. Its original root is available under Proof and hashes. Choose a leaf to highlight its path. The diagram shows six hexadecimal characters per node; complete hashes are in node descriptions and the details. Wide trees scroll within their own area.

Under Proof and hashes, change the candidate text and press Verify: the existing sibling hashes are folded in order against the displayed root without rebuilding the tree. Matching a locally generated root does not establish authenticity; that requires a trusted root. Input changes, cancellation and navigation discard pending results; an individual Web Crypto digest cannot itself be interrupted. A restored result is a saved snapshot, not a new cryptographic check; Verify checks again. Damaged tree snapshots are discarded while their raw input is kept. States above automatic storage capacity stay live while navigating within the app, show a warning and retain the previous saved copy after reload. Export before reloading. Wide trees scroll locally to the chosen leaf; the complete root remains above the diagram.

Only input values are remembered in this browser. Calculated results and experiment histories are not saved.