ListUtils gives developers 33 server-side list actions that native O11 lacks or makes painful to write. Coverage: index-based operations (Pop, PopMultiple, SplitAt, UpdateAt, UpdateMultipleAt); condition-based filtering with 9 operators and multi-condition AND/OR logic (PopByCondition, PopByConditions, Partition, PartitionByConditions, ReplaceWhere); transformations (Chunk, DistinctBy, Slice, Shuffle, Reverse, Flatten, Sample); aggregations (MinBy, MaxBy, Sum, Avg, Min, Max, Count, CountDistinct); and set / relational operations (Zip, GroupBy, ZipGroupBy, Difference, Intersect, Union, plus N-key composite and M-list variants).

Problems solved: no more Server Actions with nested For Each loops and temporary lists; no more per-Structure extensions; no more hand-authoring JSON to pass filter conditions.

Works with any Structure List via JSON Serialize / Deserialize. Nested paths (Address.City), array indexing (Items[0], Tags[-1]). Zero runtime deps. Stateless. Null-safe.