using a transaction processor of a first computer, receiving a request from a second computer via a data communication network to verify a first transaction ledger in comparison to a second transaction ledger, the request identifying the first transaction ledger and the second transaction ledger, each of the first transaction ledger and the second transaction ledger being digitally stored in a networked online data storage device accessible to the transaction processor;

using the transaction processor, accessing the first transaction ledger and the second transaction ledger and converting the first transaction ledger and the second transaction ledger to a normalized data format;

using the transaction processor, executing one or more cryptographic one-way hash algorithms over the first transaction ledger and the second transaction ledger to create and store in memory a first hash tree for the first transaction ledger and a second hash tree for the second transaction ledger;

using the transaction processor, recursively traversing corresponding nodes of the first hash tree and the second hash tree until a discrepancy is found between a first verification value for a current node of the first hash tree and a second verification value for a corresponding node of the second hash tree and recursively continuing traversal until reaching corresponding leaf nodes of the first hash tree and the second hash tree; and

using the transaction processor, forming and transmitting to the second computer, via the data communication network, a response to the request based on a comparison of the first verification value and the second verification value, the response comprising one or more of: a notification of inconsistency between the first transaction ledger and the second transaction ledger; and a notification of records from the first transaction ledger and the second transaction ledger represented by the corresponding leaf nodes of the first hash tree and the second hash tree.