Variants now exist that allow for an explicit bias based on "key weights," meaning frequently accessed data can be placed higher in the tree for even faster retrieval.
New "just-in-time" models have been developed that use an expected constant number of bits ( Updated Zipzip
Like their predecessors, they are history-independent , meaning the tree's final structure depends only on the keys it contains, not the order in which they were inserted or deleted. Current Developments (2025–2026) Variants now exist that allow for an explicit
Recent research published in early 2026 has expanded the utility of these structures: they are history-independent