The fastest, most feature-complete in-memory cache for Dart and Flutter. HashMap + custom doubly-linked LRU list. Absolute, sliding, and change-token expiration. Priority eviction with byte-size limits. Anti-stampede GetOrCreate. Post-eviction callbacks. Fully synchronous. Inspired by Microsoft.Extensions.Caching.Memory. Dual-licensed: AGPL v3 for open-source, commercial license available.