Visualize Merkle tree Do you have any ideas or suggestions how to visualize Merkle trees? 

For our open source project "Open Tracking" we create Merkle trees for thousands of tracking counters before putting the root hash to a bitcoin transaction with OP_RETURN script. 

Each hour we merklize state of all active counters for ~20,000 domains and thus we have the tree with 20k elements at the base level. 

My first idea was to visualize it in spreadsheet-style. A first column will be level one, a second column will be level two etc.
You can serialize a binary tree with n leafs (such as a merkle tree) as an array of 2n-1 entries. The root is entry 1 and for each node the left child is at position 2n and the right child is at position 2n+1. This gives you a compact representation of the entire tree.

Another option would be to just have the n leaf nodes in a list since the inner nodes are actually generated from the leafs.

Both need to be checked by a program, since checking the validity of a tree involves computing cryptographic hashes. Visualizing them in a human readable format does not really provide any security if it cannot be verified.