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MemoryLangChain

LangMem

Long-term memory SDK that lets agents learn and adapt over time.

Category
Memory
Pricing
FREE
Source
Open source
Platforms
APICLI
Models
BYO key / model
Verified
Jun 13, 2026

A memory toolkit for AI agents that extracts and stores facts from conversations and refines agent behavior through prompt updates. Exposes semantic, episodic, and procedural memory via a storage-agnostic core API plus tools agents can call during or after a conversation.

Pros & cons

  • Semantic, episodic, procedural memory
  • Storage- and framework-agnostic core API
  • Native LangGraph integration
  • MIT-licensed and free
  • Most value inside the LangChain stack
  • Young SDK, evolving API
  • You wire up your own storage layer

Tags

Further reading

Alternatives to LangMem (4)

View all Memory →
  • View mem0 details
    MemoryFREEMIUMOpen core

    mem0

    Mem0

    Long-term memory layer for AI agents. Self-hostable.

    Persistent memory store + retrieval pipeline for agent applications. Handles per-user/per-session/per-agent scope cleanly; pairs with OpenAI, Anthropic, and local models.

    Worth knowing

    A YC S24 company that pivoted from the Embedchain RAG framework; raised a $24M Series A from YC and Peak XV in 2025.

    • memory
    • agents
    • rag
    • self-hosted
    Open
  • View Letta details
    MemoryFREEMIUMOpen core

    Letta

    Letta

    Stateful agents with structured memory. Successor to MemGPT.

    Open-source framework for building stateful agents — memory blocks, context-window management, tool-use primitives baked in. Useful as a reference architecture for long-running agents.

    Worth knowing

    Spun out of UC Berkeley's Sky Lab in 2024 by the MemGPT authors, with a $10M seed led by Felicis.

    • memory
    • stateful
    • agents
    • open-source
    Open
  • View Zep details
    MemoryFREEMIUM

    Zep

    Zep

    Temporal knowledge-graph memory for AI agents.

    Memory layer that gives agents long-term context by building a temporal knowledge graph from chat history and business data, tracking how facts evolve over time. It's powered by Graphiti, Zep's Apache-2.0 open-source temporal graph engine, with Zep Cloud offering a managed, credit-based service on top. Used to keep agent context relevant as conversations and data grow.

    Worth knowing

    A YC W24 startup; published a 2025 arXiv paper benchmarking its temporal knowledge-graph memory against prior agent-memory work.

    • memory
    • agents
    • knowledge-graph
    • temporal
    • +1
    Open
  • View Cognee details
    MemoryFREEMIUMOpen core

    Cognee

    Cognee

    Open-source memory for AI agents.

    An open-source semantic memory layer for AI agents. Cognee ingests documents, relational data, and system context, then runs an Extract-Cognify-Load pipeline that uses an LLM to build a knowledge graph with embeddings and relationships. Agents query it for durable, cross-session context that captures how concepts connect. Self-host the Python SDK for free, or use the managed cloud tiers.

    Worth knowing

    Berlin-based; raised a $7.5M seed in Feb 2026 led by Pebblebed (run by OpenAI and FAIR co-founders).

    • agent-memory
    • knowledge-graph
    • rag
    • open-source
    Open
Open LangMem