AI tool comparison
MemPalace vs Mnemos
Which one should you ship with? Here is the side-by-side panel verdict, pricing read, reviewer split, and community vote comparison.
Developer Tools
MemPalace
Persistent cross-session memory for any LLM — local, free, 96% LongMemEval
75%
Panel ship
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Community
Free
Entry
MemPalace is a free, open-source AI memory system that gives large language models persistent, cross-session memory. It accumulated over 43,000 GitHub stars within a week of launch — one of the fastest open-source AI project takeoffs of 2026. Unlike systems that use AI to summarize memories (lossy by design), MemPalace stores all conversation data verbatim and uses vector search via ChromaDB and SQLite to retrieve relevant memories. The storage metaphor is architecturally literal: people and projects become 'wings', topics become 'rooms', and original content lives in 'drawers' — enabling scoped search rather than flat corpus retrieval. Memory retrieval costs just ~170 tokens, making it practical even in cost-sensitive deployments. On the LongMemEval benchmark it scores 96.6% raw (100% in hybrid mode, though the hybrid methodology has faced some independent scrutiny). It runs entirely locally at zero API cost, meaning no cloud dependency and no privacy leakage. The project has been independently validated on production agentic workflows and is already being integrated into agent frameworks.
Developer Tools
Mnemos
Local vector memory for Claude Desktop with 3D conversation visualization
75%
Panel ship
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Community
Free
Entry
Claude Desktop has no memory across sessions. You close the window and it forgets everything. Mnemos is an open-source MCP server that fixes this by watching your conversation files in real-time, indexing them with local ONNX embeddings (MiniLM-L6-v2), and enabling hybrid semantic + keyword search — all without a single byte leaving your machine. The v1.1 release adds a genuinely striking feature: a 3D semantic visualization that maps your conversations into a clustered constellation using UMAP dimensionality reduction and Three.js. You can scrub through a chronological timeline and watch the knowledge graph build in real time. It is, frankly, prettier than it needs to be. Built on .NET 9, SQLite FTS5, and React/Vite, Mnemos is one of the more technically ambitious "Claude memory" projects to appear on HN this week. The offline-first, MIT-licensed approach puts it in a different league from cloud-synced alternatives.
Reviewer scorecard
“Verbatim storage avoids the lossy-summary trap that plagues most memory systems. ChromaDB + SQLite locally is a practical stack with minimal operational overhead, and the 170-token retrieval cost is genuinely low. Worth evaluating before paying for any memory-as-a-service layer.”
“This solves a real, painful problem with zero cloud dependency. The hybrid FTS5 + vector search is the right architecture — you get speed and semantic richness without compromising privacy. The .NET 9 stack is slightly niche but the setup looks smooth.”
“The 100% hybrid LongMemEval score was achieved through targeted fixes for specific failing test cases, and independent reviewers have flagged methodology concerns. 43K GitHub stars in a week is hype velocity, not production validation. Wait for real-world deployments before betting critical workflows on this.”
“It is a one-person Show HN project posted literally today with 2 GitHub stars. The 3D visualization is cool but has nothing to do with actually improving recall quality. Also: how often do you actually need to search old Claude conversations vs. just starting fresh?”
“Persistent local AI memory is the missing infrastructure layer in most agent architectures. MemPalace's hierarchical 'palace' structure — wings, rooms, drawers — is a more principled approach to memory organization than flat vector search, and it points toward how agents will eventually manage long-horizon knowledge.”
“Local-first AI memory is the correct long-term architecture. Every AI system we rely on should have this kind of persistent, private, searchable context layer. Mnemos is a prototype of what OS-level AI memory will eventually look like, and seeing it built today matters.”
“Being able to pick up a creative project where you left it — with full context intact across sessions — fundamentally changes how AI fits into long-duration creative work. Local storage means zero privacy leakage. This is the boring infrastructure that unlocks actually useful creative AI workflows.”
“The 3D constellation visualization genuinely excites me — there is art in watching your conversation history render as a navigable space. For writers and researchers who use Claude heavily, the ability to rediscover old threads through semantic search could unlock something meaningful.”
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