Add persistence

Many AI applications need memory to share context across multiple interactions. LangGraph supports two types of memory essential for building conversational agents:

• Short-term memory: Tracks the ongoing conversation by maintaining message history within a session.
• Long-term memory: Stores user-specific or application-level data across sessions.

Terminology

In LangGraph:

• Short-term memory is also referred to as thread-level memory.
• Long-term memory is also called cross-thread memory.

A thread represents a sequence of related runs grouped by the same thread_id.

Add short-term memory

Short-term memory (thread-level persistence) enables agents to track multi-turn conversations. To add short-term memory:

^{API Reference: init_chat_model | StateGraph | START | InMemorySaver}

from langchain.chat_models import init_chat_model
from langgraph.graph import StateGraph, MessagesState, START

from langgraph.checkpoint.memory import InMemorySaver

model = init_chat_model(model="anthropic:claude-3-5-haiku-latest")


def call_model(state: MessagesState):
    response = model.invoke(state["messages"])
    return {"messages": response}


builder = StateGraph(MessagesState)
builder.add_node(call_model)
builder.add_edge(START, "call_model")

checkpointer = InMemorySaver()
graph = builder.compile(checkpointer=checkpointer)

config = {
    "configurable": {
        "thread_id": "1"
    }
}

for chunk in graph.stream(
    {"messages": [{"role": "user", "content": "hi! I'm bob"}]},
    config,
    stream_mode="values",
):
    chunk["messages"][-1].pretty_print()

for chunk in graph.stream(
    {"messages": [{"role": "user", "content": "what's my name?"}]},
    config,
    stream_mode="values",
):
    chunk["messages"][-1].pretty_print()

================================ Human Message =================================

hi! I'm bob
================================== Ai Message ==================================

Hi Bob! How are you doing today? Is there anything I can help you with?
================================ Human Message =================================

what's my name?
================================== Ai Message ==================================

Your name is Bob.

Not needed for LangGraph API users

If you're using the LangGraph API, don't need to provide checkpointer when compiling the graph. The API automatically handles checkpointing for you.

Use in production

In production, you would want to use a checkpointer backed by a database:

^{API Reference: PostgresSaver}

from langgraph.checkpoint.postgres import PostgresSaver

DB_URI = "postgresql://postgres:postgres@localhost:5442/postgres?sslmode=disable"
with PostgresSaver.from_conn_string(DB_URI) as checkpointer:
    builder = StateGraph(...)
    graph = builder.compile(checkpointer=checkpointer)

Example: using Postgres checkpointer

pip install -U psycopg psycopg-pool langgraph langgraph-checkpoint-postgres

Setup

You need to call checkpointer.setup() the first time you're using Postgres checkpointer

SyncAsync

from langchain.chat_models import init_chat_model
from langgraph.graph import StateGraph, MessagesState, START
from langgraph.checkpoint.postgres import PostgresSaver

model = init_chat_model(model="anthropic:claude-3-5-haiku-latest")

DB_URI = "postgresql://postgres:postgres@localhost:5442/postgres?sslmode=disable"
with PostgresSaver.from_conn_string(DB_URI) as checkpointer:
    # checkpointer.setup()

    def call_model(state: MessagesState):
        response = model.invoke(state["messages"])
        return {"messages": response}

    builder = StateGraph(MessagesState)
    builder.add_node(call_model)
    builder.add_edge(START, "call_model")

    graph = builder.compile(checkpointer=checkpointer)

    config = {
        "configurable": {
            "thread_id": "1"
        }
    }

    for chunk in graph.stream(
        {"messages": [{"role": "user", "content": "hi! I'm bob"}]},
        config,
        stream_mode="values"
    ):
        chunk["messages"][-1].pretty_print()

    for chunk in graph.stream(
        {"messages": [{"role": "user", "content": "what's my name?"}]},
        config,
        stream_mode="values"
    ):
        chunk["messages"][-1].pretty_print()

from langchain.chat_models import init_chat_model
from langgraph.graph import StateGraph, MessagesState, START
from langgraph.checkpoint.postgres.aio import AsyncPostgresSaver

model = init_chat_model(model="anthropic:claude-3-5-haiku-latest")

DB_URI = "postgresql://postgres:postgres@localhost:5442/postgres?sslmode=disable"
async with AsyncPostgresSaver.from_conn_string(DB_URI) as checkpointer:
    # await checkpointer.setup()

    async def call_model(state: MessagesState):
        response = await model.ainvoke(state["messages"])
        return {"messages": response}

    builder = StateGraph(MessagesState)
    builder.add_node(call_model)
    builder.add_edge(START, "call_model")

    graph = builder.compile(checkpointer=checkpointer)

    config = {
        "configurable": {
            "thread_id": "1"
        }
    }

    async for chunk in graph.astream(
        {"messages": [{"role": "user", "content": "hi! I'm bob"}]},
        config,
        stream_mode="values"
    ):
        chunk["messages"][-1].pretty_print()

    async for chunk in graph.astream(
        {"messages": [{"role": "user", "content": "what's my name?"}]},
        config,
        stream_mode="values"
    ):
        chunk["messages"][-1].pretty_print()

Example: using MongoDB checkpointer

pip install -U pymongo langgraph langgraph-checkpoint-mongodb

Setup

To use the MongoDB checkpointer, you will need a MongoDB cluster. Follow this guide to create a cluster if you don't already have one.

SyncAsync

from langchain.chat_models import init_chat_model
from langgraph.graph import StateGraph, MessagesState, START
from langgraph.checkpoint.mongodb import MongoDBSaver

model = init_chat_model(model="anthropic:claude-3-5-haiku-latest")

DB_URI = "localhost:27017"
with MongoDBSaver.from_conn_string(DB_URI) as checkpointer:

    def call_model(state: MessagesState):
        response = model.invoke(state["messages"])
        return {"messages": response}

    builder = StateGraph(MessagesState)
    builder.add_node(call_model)
    builder.add_edge(START, "call_model")

    graph = builder.compile(checkpointer=checkpointer)

    config = {
        "configurable": {
            "thread_id": "1"
        }
    }

    for chunk in graph.stream(
        {"messages": [{"role": "user", "content": "hi! I'm bob"}]},
        config,
        stream_mode="values"
    ):
        chunk["messages"][-1].pretty_print()

    for chunk in graph.stream(
        {"messages": [{"role": "user", "content": "what's my name?"}]},
        config,
        stream_mode="values"
    ):
        chunk["messages"][-1].pretty_print()

from langchain.chat_models import init_chat_model
from langgraph.graph import StateGraph, MessagesState, START
from langgraph.checkpoint.mongodb.aio import AsyncMongoDBSaver

model = init_chat_model(model="anthropic:claude-3-5-haiku-latest")

DB_URI = "localhost:27017"
async with AsyncMongoDBSaver.from_conn_string(DB_URI) as checkpointer:

    async def call_model(state: MessagesState):
        response = await model.ainvoke(state["messages"])
        return {"messages": response}

    builder = StateGraph(MessagesState)
    builder.add_node(call_model)
    builder.add_edge(START, "call_model")

    graph = builder.compile(checkpointer=checkpointer)

    config = {
        "configurable": {
            "thread_id": "1"
        }
    }

    async for chunk in graph.astream(
        {"messages": [{"role": "user", "content": "hi! I'm bob"}]},
        config,
        stream_mode="values"
    ):
        chunk["messages"][-1].pretty_print()

    async for chunk in graph.astream(
        {"messages": [{"role": "user", "content": "what's my name?"}]},
        config,
        stream_mode="values"
    ):
        chunk["messages"][-1].pretty_print()

Example: using Redis checkpointer

pip install -U langgraph langgraph-checkpoint-redis

Setup

You need to call checkpointer.setup() the first time you're using Redis checkpointer

SyncAsync

from langchain.chat_models import init_chat_model
from langgraph.graph import StateGraph, MessagesState, START
from langgraph.checkpoint.redis import RedisSaver

model = init_chat_model(model="anthropic:claude-3-5-haiku-latest")

DB_URI = "redis://localhost:6379"
with RedisSaver.from_conn_string(DB_URI) as checkpointer:
    # checkpointer.setup()

    def call_model(state: MessagesState):
        response = model.invoke(state["messages"])
        return {"messages": response}

    builder = StateGraph(MessagesState)
    builder.add_node(call_model)
    builder.add_edge(START, "call_model")

    graph = builder.compile(checkpointer=checkpointer)

    config = {
        "configurable": {
            "thread_id": "1"
        }
    }

    for chunk in graph.stream(
        {"messages": [{"role": "user", "content": "hi! I'm bob"}]},
        config,
        stream_mode="values"
    ):
        chunk["messages"][-1].pretty_print()

    for chunk in graph.stream(
        {"messages": [{"role": "user", "content": "what's my name?"}]},
        config,
        stream_mode="values"
    ):
        chunk["messages"][-1].pretty_print()

from langchain.chat_models import init_chat_model
from langgraph.graph import StateGraph, MessagesState, START
from langgraph.checkpoint.redis.aio import AsyncRedisSaver

model = init_chat_model(model="anthropic:claude-3-5-haiku-latest")

DB_URI = "redis://localhost:6379"
async with AsyncRedisSaver.from_conn_string(DB_URI) as checkpointer:
    # await checkpointer.asetup()

    async def call_model(state: MessagesState):
        response = await model.ainvoke(state["messages"])
        return {"messages": response}

    builder = StateGraph(MessagesState)
    builder.add_node(call_model)
    builder.add_edge(START, "call_model")

    graph = builder.compile(checkpointer=checkpointer)

    config = {
        "configurable": {
            "thread_id": "1"
        }
    }

    async for chunk in graph.astream(
        {"messages": [{"role": "user", "content": "hi! I'm bob"}]},
        config,
        stream_mode="values"
    ):
        chunk["messages"][-1].pretty_print()

    async for chunk in graph.astream(
        {"messages": [{"role": "user", "content": "what's my name?"}]},
        config,
        stream_mode="values"
    ):
        chunk["messages"][-1].pretty_print()     

Use with subgraphs

If your graph contains subgraphs, you only need to provide the checkpointer when compiling the parent graph. LangGraph will automatically propagate the checkpointer to the child subgraphs.

^{API Reference: START | StateGraph | InMemorySaver}

from langgraph.graph import START, StateGraph
from langgraph.checkpoint.memory import InMemorySaver
from typing import TypedDict

class State(TypedDict):
    foo: str

# Subgraph

def subgraph_node_1(state: State):
    return {"foo": state["foo"] + "bar"}

subgraph_builder = StateGraph(State)
subgraph_builder.add_node(subgraph_node_1)
subgraph_builder.add_edge(START, "subgraph_node_1")
subgraph = subgraph_builder.compile()

# Parent graph

def node_1(state: State):
    return {"foo": "hi! " + state["foo"]}

builder = StateGraph(State)
builder.add_node("node_1", subgraph)
builder.add_edge(START, "node_1")

checkpointer = InMemorySaver()
graph = builder.compile(checkpointer=checkpointer)

If you want the subgraph to have its own memory, you can compile it with checkpointer=True. This is useful in multi-agent systems, if you want agents to keep track of their internal message histories:

subgraph_builder = StateGraph(...)
subgraph = subgraph_builder.compile(checkpointer=True)

Use with Functional API

To add short-term memory to a Functional API LangGraph workflow:

1. Pass checkpointer instance to the entrypoint() decorator:

   from langgraph.func import entrypoint
   
   @entrypoint(checkpointer=checkpointer)
   def workflow(inputs)
       ...
   

2. Optionally expose previous parameter in the workflow function signature:

   @entrypoint(checkpointer=checkpointer)
   def workflow(
       inputs,
       *,
       # you can optionally specify `previous` in the workflow function signature
       # to access the return value from the workflow as of the last execution
       previous
   ):
       previous = previous or []
       combined_inputs = previous + inputs
       result = do_something(combined_inputs)
       ...
   

3. Optionally choose which values will be returned from the workflow and which will be saved by the checkpointer as previous:

   @entrypoint(checkpointer=checkpointer)
   def workflow(inputs, *, previous):
       ...
       result = do_something(...)
       return entrypoint.final(value=result, save=combine(inputs, result))
   

Example: add short-term memory to Functional API workflow

from langchain_core.messages import AnyMessage
from langgraph.graph import add_messages
from langgraph.func import entrypoint, task
from langgraph.checkpoint.memory import InMemorySaver

@task
def call_model(messages: list[AnyMessage]):
    response = model.invoke(messages)
    return response

checkpointer = InMemorySaver()

@entrypoint(checkpointer=checkpointer)
def workflow(inputs: list[AnyMessage], *, previous: list[AnyMessage]):
    if previous:
        inputs = add_messages(previous, inputs)

    response = call_model(inputs).result()
    return entrypoint.final(value=response, save=add_messages(inputs, response))

config = {
    "configurable": {
        "thread_id": "1"
    }
}

for chunk in workflow.invoke(
    [{"role": "user", "content": "hi! I'm bob"}],
    config,
    stream_mode="values",
):
    chunk.pretty_print()

for chunk in workflow.stream(
    [{"role": "user", "content": "what's my name?"}],
    config,
    stream_mode="values",
):
    chunk.pretty_print()

Manage checkpoints

You can view and delete the information stored by the checkpointer:

View thread state (checkpoint)

Graph/Functional APICheckpointer API

config = {
    "configurable": {
        "thread_id": "1",
        # optionally provide an ID for a specific checkpoint,
        # otherwise the latest checkpoint is shown
        # "checkpoint_id": "1f029ca3-1f5b-6704-8004-820c16b69a5a"

    }
}
graph.get_state(config)

StateSnapshot(
    values={'messages': [HumanMessage(content="hi! I'm bob"), AIMessage(content='Hi Bob! How are you doing today?), HumanMessage(content="what's my name?"), AIMessage(content='Your name is Bob.')]}, next=(), 
    config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f029ca3-1f5b-6704-8004-820c16b69a5a'}},
    metadata={
        'source': 'loop',
        'writes': {'call_model': {'messages': AIMessage(content='Your name is Bob.')}},
        'step': 4,
        'parents': {},
        'thread_id': '1'
    },
    created_at='2025-05-05T16:01:24.680462+00:00',
    parent_config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f029ca3-1790-6b0a-8003-baf965b6a38f'}}, 
    tasks=(),
    interrupts=()
)

config = {
    "configurable": {
        "thread_id": "1",
        # optionally provide an ID for a specific checkpoint,
        # otherwise the latest checkpoint is shown
        # "checkpoint_id": "1f029ca3-1f5b-6704-8004-820c16b69a5a"

    }
}
checkpointer.get_tuple(config)

CheckpointTuple(
    config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f029ca3-1f5b-6704-8004-820c16b69a5a'}},
    checkpoint={
        'v': 3,
        'ts': '2025-05-05T16:01:24.680462+00:00',
        'id': '1f029ca3-1f5b-6704-8004-820c16b69a5a',
        'channel_versions': {'__start__': '00000000000000000000000000000005.0.5290678567601859', 'messages': '00000000000000000000000000000006.0.3205149138784782', 'branch:to:call_model': '00000000000000000000000000000006.0.14611156755133758'}, 'versions_seen': {'__input__': {}, '__start__': {'__start__': '00000000000000000000000000000004.0.5736472536395331'}, 'call_model': {'branch:to:call_model': '00000000000000000000000000000005.0.1410174088651449'}},
        'channel_values': {'messages': [HumanMessage(content="hi! I'm bob"), AIMessage(content='Hi Bob! How are you doing today?), HumanMessage(content="what's my name?"), AIMessage(content='Your name is Bob.')]},
        'pending_sends': []
    },
    metadata={
        'source': 'loop',
        'writes': {'call_model': {'messages': AIMessage(content='Your name is Bob.')}},
        'step': 4,
        'parents': {},
        'thread_id': '1'
    },
    parent_config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f029ca3-1790-6b0a-8003-baf965b6a38f'}},
    pending_writes=[]
)

View the history of the thread (checkpoints)

Graph/Functional APICheckpointer API

config = {
    "configurable": {
        "thread_id": "1"
    }
}
list(graph.get_state_history(config))

[
    StateSnapshot(
        values={'messages': [HumanMessage(content="hi! I'm bob"), AIMessage(content='Hi Bob! How are you doing today? Is there anything I can help you with?'), HumanMessage(content="what's my name?"), AIMessage(content='Your name is Bob.')]}, 
        next=(), 
        config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f029ca3-1f5b-6704-8004-820c16b69a5a'}}, 
        metadata={'source': 'loop', 'writes': {'call_model': {'messages': AIMessage(content='Your name is Bob.')}}, 'step': 4, 'parents': {}, 'thread_id': '1'},
        created_at='2025-05-05T16:01:24.680462+00:00',
        parent_config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f029ca3-1790-6b0a-8003-baf965b6a38f'}},
        tasks=(),
        interrupts=()
    ),
    StateSnapshot(
        values={'messages': [HumanMessage(content="hi! I'm bob"), AIMessage(content='Hi Bob! How are you doing today? Is there anything I can help you with?'), HumanMessage(content="what's my name?")]}, 
        next=('call_model',), 
        config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f029ca3-1790-6b0a-8003-baf965b6a38f'}},
        metadata={'source': 'loop', 'writes': None, 'step': 3, 'parents': {}, 'thread_id': '1'},
        created_at='2025-05-05T16:01:23.863421+00:00',
        parent_config={...}
        tasks=(PregelTask(id='8ab4155e-6b15-b885-9ce5-bed69a2c305c', name='call_model', path=('__pregel_pull', 'call_model'), error=None, interrupts=(), state=None, result={'messages': AIMessage(content='Your name is Bob.')}),),
        interrupts=()
    ),
    StateSnapshot(
        values={'messages': [HumanMessage(content="hi! I'm bob"), AIMessage(content='Hi Bob! How are you doing today? Is there anything I can help you with?')]}, 
        next=('__start__',), 
        config={...}, 
        metadata={'source': 'input', 'writes': {'__start__': {'messages': [{'role': 'user', 'content': "what's my name?"}]}}, 'step': 2, 'parents': {}, 'thread_id': '1'},
        created_at='2025-05-05T16:01:23.863173+00:00',
        parent_config={...}
        tasks=(PregelTask(id='24ba39d6-6db1-4c9b-f4c5-682aeaf38dcd', name='__start__', path=('__pregel_pull', '__start__'), error=None, interrupts=(), state=None, result={'messages': [{'role': 'user', 'content': "what's my name?"}]}),),
        interrupts=()
    ),
    StateSnapshot(
        values={'messages': [HumanMessage(content="hi! I'm bob"), AIMessage(content='Hi Bob! How are you doing today? Is there anything I can help you with?')]}, 
        next=(), 
        config={...}, 
        metadata={'source': 'loop', 'writes': {'call_model': {'messages': AIMessage(content='Hi Bob! How are you doing today? Is there anything I can help you with?')}}, 'step': 1, 'parents': {}, 'thread_id': '1'},
        created_at='2025-05-05T16:01:23.862295+00:00',
        parent_config={...}
        tasks=(),
        interrupts=()
    ),
    StateSnapshot(
        values={'messages': [HumanMessage(content="hi! I'm bob")]}, 
        next=('call_model',), 
        config={...}, 
        metadata={'source': 'loop', 'writes': None, 'step': 0, 'parents': {}, 'thread_id': '1'}, 
        created_at='2025-05-05T16:01:22.278960+00:00', 
        parent_config={...}
        tasks=(PregelTask(id='8cbd75e0-3720-b056-04f7-71ac805140a0', name='call_model', path=('__pregel_pull', 'call_model'), error=None, interrupts=(), state=None, result={'messages': AIMessage(content='Hi Bob! How are you doing today? Is there anything I can help you with?')}),), 
        interrupts=()
    ),
    StateSnapshot(
        values={'messages': []}, 
        next=('__start__',), 
        config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f029ca3-0870-6ce2-bfff-1f3f14c3e565'}},
        metadata={'source': 'input', 'writes': {'__start__': {'messages': [{'role': 'user', 'content': "hi! I'm bob"}]}}, 'step': -1, 'parents': {}, 'thread_id': '1'}, 
        created_at='2025-05-05T16:01:22.277497+00:00', 
        parent_config=None,
        tasks=(PregelTask(id='d458367b-8265-812c-18e2-33001d199ce6', name='__start__', path=('__pregel_pull', '__start__'), error=None, interrupts=(), state=None, result={'messages': [{'role': 'user', 'content': "hi! I'm bob"}]}),), 
        interrupts=()
    )
]       

config = {
    "configurable": {
        "thread_id": "1"
    }
}
list(checkpointer.list(config))

[
    CheckpointTuple(
        config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f029ca3-1f5b-6704-8004-820c16b69a5a'}}, 
        checkpoint={
            'v': 3, 
            'ts': '2025-05-05T16:01:24.680462+00:00', 
            'id': '1f029ca3-1f5b-6704-8004-820c16b69a5a', 
            'channel_versions': {'__start__': '00000000000000000000000000000005.0.5290678567601859', 'messages': '00000000000000000000000000000006.0.3205149138784782', 'branch:to:call_model': '00000000000000000000000000000006.0.14611156755133758'}, 
            'versions_seen': {'__input__': {}, '__start__': {'__start__': '00000000000000000000000000000004.0.5736472536395331'}, 'call_model': {'branch:to:call_model': '00000000000000000000000000000005.0.1410174088651449'}},
            'channel_values': {'messages': [HumanMessage(content="hi! I'm bob"), AIMessage(content='Hi Bob! How are you doing today? Is there anything I can help you with?'), HumanMessage(content="what's my name?"), AIMessage(content='Your name is Bob.')]}, 'pending_sends': []
        },
        metadata={'source': 'loop', 'writes': {'call_model': {'messages': AIMessage(content='Your name is Bob.')}}, 'step': 4, 'parents': {}, 'thread_id': '1'}, 
        parent_config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f029ca3-1790-6b0a-8003-baf965b6a38f'}}, 
        pending_writes=[]
    ),
    CheckpointTuple(
        config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f029ca3-1790-6b0a-8003-baf965b6a38f'}},
        checkpoint={
            'v': 3, 
            'ts': '2025-05-05T16:01:23.863421+00:00', 
            'id': '1f029ca3-1790-6b0a-8003-baf965b6a38f', 
            'channel_versions': {'__start__': '00000000000000000000000000000005.0.5290678567601859', 'messages': '00000000000000000000000000000005.0.7935064215293443', 'branch:to:call_model': '00000000000000000000000000000005.0.1410174088651449'}, 
            'versions_seen': {'__input__': {}, '__start__': {'__start__': '00000000000000000000000000000004.0.5736472536395331'}, 'call_model': {'branch:to:call_model': '00000000000000000000000000000002.0.9300422176788571'}}, 
            'channel_values': {'messages': [HumanMessage(content="hi! I'm bob"), AIMessage(content='Hi Bob! How are you doing today? Is there anything I can help you with?'), HumanMessage(content="what's my name?")], 'branch:to:call_model': None}, 
            'pending_sends': []
        }, 
        metadata={'source': 'loop', 'writes': None, 'step': 3, 'parents': {}, 'thread_id': '1'}, 
        parent_config={...}, 
        pending_writes=[('8ab4155e-6b15-b885-9ce5-bed69a2c305c', 'messages', AIMessage(content='Your name is Bob.'))]
    ),
    CheckpointTuple(
        config={...}, 
        checkpoint={
            'v': 3, 
            'ts': '2025-05-05T16:01:23.863173+00:00', 
            'id': '1f029ca3-1790-616e-8002-9e021694a0cd', 
            'channel_versions': {'__start__': '00000000000000000000000000000004.0.5736472536395331', 'messages': '00000000000000000000000000000003.0.7056767754077798', 'branch:to:call_model': '00000000000000000000000000000003.0.22059023329132854'}, 
            'versions_seen': {'__input__': {}, '__start__': {'__start__': '00000000000000000000000000000001.0.7040775356287469'}, 'call_model': {'branch:to:call_model': '00000000000000000000000000000002.0.9300422176788571'}}, 
            'channel_values': {'__start__': {'messages': [{'role': 'user', 'content': "what's my name?"}]}, 'messages': [HumanMessage(content="hi! I'm bob"), AIMessage(content='Hi Bob! How are you doing today? Is there anything I can help you with?')]}, 
            'pending_sends': []
        }, 
        metadata={'source': 'input', 'writes': {'__start__': {'messages': [{'role': 'user', 'content': "what's my name?"}]}}, 'step': 2, 'parents': {}, 'thread_id': '1'}, 
        parent_config={...}, 
        pending_writes=[('24ba39d6-6db1-4c9b-f4c5-682aeaf38dcd', 'messages', [{'role': 'user', 'content': "what's my name?"}]), ('24ba39d6-6db1-4c9b-f4c5-682aeaf38dcd', 'branch:to:call_model', None)]
    ),
    CheckpointTuple(
        config={...}, 
        checkpoint={
            'v': 3, 
            'ts': '2025-05-05T16:01:23.862295+00:00', 
            'id': '1f029ca3-178d-6f54-8001-d7b180db0c89', 
            'channel_versions': {'__start__': '00000000000000000000000000000002.0.18673090920108737', 'messages': '00000000000000000000000000000003.0.7056767754077798', 'branch:to:call_model': '00000000000000000000000000000003.0.22059023329132854'}, 
            'versions_seen': {'__input__': {}, '__start__': {'__start__': '00000000000000000000000000000001.0.7040775356287469'}, 'call_model': {'branch:to:call_model': '00000000000000000000000000000002.0.9300422176788571'}}, 
            'channel_values': {'messages': [HumanMessage(content="hi! I'm bob"), AIMessage(content='Hi Bob! How are you doing today? Is there anything I can help you with?')]}, 
            'pending_sends': []
        }, 
        metadata={'source': 'loop', 'writes': {'call_model': {'messages': AIMessage(content='Hi Bob! How are you doing today? Is there anything I can help you with?')}}, 'step': 1, 'parents': {}, 'thread_id': '1'}, 
        parent_config={...}, 
        pending_writes=[]
    ),
    CheckpointTuple(
        config={...}, 
        checkpoint={
            'v': 3, 
            'ts': '2025-05-05T16:01:22.278960+00:00', 
            'id': '1f029ca3-0874-6612-8000-339f2abc83b1', 
            'channel_versions': {'__start__': '00000000000000000000000000000002.0.18673090920108737', 'messages': '00000000000000000000000000000002.0.30296526818059655', 'branch:to:call_model': '00000000000000000000000000000002.0.9300422176788571'}, 
            'versions_seen': {'__input__': {}, '__start__': {'__start__': '00000000000000000000000000000001.0.7040775356287469'}}, 
            'channel_values': {'messages': [HumanMessage(content="hi! I'm bob")], 'branch:to:call_model': None}, 
            'pending_sends': []
        }, 
        metadata={'source': 'loop', 'writes': None, 'step': 0, 'parents': {}, 'thread_id': '1'}, 
        parent_config={...}, 
        pending_writes=[('8cbd75e0-3720-b056-04f7-71ac805140a0', 'messages', AIMessage(content='Hi Bob! How are you doing today? Is there anything I can help you with?'))]
    ),
    CheckpointTuple(
        config={'configurable': {'thread_id': '1', 'checkpoint_ns': '', 'checkpoint_id': '1f029ca3-0870-6ce2-bfff-1f3f14c3e565'}}, 
        checkpoint={
            'v': 3, 
            'ts': '2025-05-05T16:01:22.277497+00:00', 
            'id': '1f029ca3-0870-6ce2-bfff-1f3f14c3e565', 
            'channel_versions': {'__start__': '00000000000000000000000000000001.0.7040775356287469'}, 
            'versions_seen': {'__input__': {}}, 
            'channel_values': {'__start__': {'messages': [{'role': 'user', 'content': "hi! I'm bob"}]}}, 
            'pending_sends': []
        }, 
        metadata={'source': 'input', 'writes': {'__start__': {'messages': [{'role': 'user', 'content': "hi! I'm bob"}]}}, 'step': -1, 'parents': {}, 'thread_id': '1'}, 
        parent_config=None, 
        pending_writes=[('d458367b-8265-812c-18e2-33001d199ce6', 'messages', [{'role': 'user', 'content': "hi! I'm bob"}]), ('d458367b-8265-812c-18e2-33001d199ce6', 'branch:to:call_model', None)]
    )
]

Delete all checkpoints for a thread

thread_id = "1"
checkpointer.delete_thread(thread_id)

Add long-term memory

Use long-term memory (cross-thread persistence) to store user-specific or application-specific data across conversations. This is useful for applications like chatbots, where you want to remember user preferences or other information.

To use long-term memory, we need to provide a store when creating the graph:

^{API Reference: RunnableConfig | StateGraph | START | InMemorySaver}

import uuid
from typing_extensions import Annotated, TypedDict

from langchain_core.runnables import RunnableConfig
from langgraph.graph import StateGraph, MessagesState, START
from langgraph.checkpoint.memory import InMemorySaver

from langgraph.store.memory import InMemoryStore
from langgraph.store.base import BaseStore

model = init_chat_model(model="anthropic:claude-3-5-haiku-latest")


def call_model(
    state: MessagesState,
    config: RunnableConfig,
    *,
    store: BaseStore,  # (1)!
):
    user_id = config["configurable"]["user_id"]
    namespace = ("memories", user_id)
    memories = store.search(namespace, query=str(state["messages"][-1].content))
    info = "\n".join([d.value["data"] for d in memories])
    system_msg = f"You are a helpful assistant talking to the user. User info: {info}"

    # Store new memories if the user asks the model to remember
    last_message = state["messages"][-1]
    if "remember" in last_message.content.lower():
        memory = "User name is Bob"
        store.put(namespace, str(uuid.uuid4()), {"data": memory})

    response = model.invoke(
        [{"role": "system", "content": system_msg}] + state["messages"]
    )
    return {"messages": response}


builder = StateGraph(MessagesState)
builder.add_node(call_model)
builder.add_edge(START, "call_model")

checkpointer = InMemorySaver()
store = InMemoryStore()

graph = builder.compile(
    checkpointer=checkpointer,
    store=store,
)

1. This is the store we compiled the graph with

config = {
    "configurable": {
        "thread_id": "1",
        "user_id": "1",
    }
}
for chunk in graph.stream(
    {"messages": [{"role": "user", "content": "Hi! Remember: my name is Bob"}]},
    config,
    stream_mode="values",
):
    chunk["messages"][-1].pretty_print()

config = {
    "configurable": {
        "thread_id": "2",
        "user_id": "1",
    }
}

for chunk in graph.stream(
    {"messages": [{"role": "user", "content": "what is my name?"}]},
    config,
    stream_mode="values",
):
    chunk["messages"][-1].pretty_print()

================================ Human Message =================================

Hi! Remember: my name is Bob
================================== Ai Message ==================================

Hi Bob! I'll remember that your name is Bob. How are you doing today?
================================ Human Message =================================

what is my name?
================================== Ai Message ==================================

Your name is Bob.

Not needed for LangGraph API users

If you're using the LangGraph API, don't need to provide store when compiling the graph. The API automatically handles storage infrastructure for you.

Use in production

In production, you would want to use a checkpointer backed by a database:

^{API Reference: PostgresSaver}

from langgraph.checkpoint.postgres import PostgresSaver

DB_URI = "postgresql://postgres:postgres@localhost:5442/postgres?sslmode=disable"
with PostgresStore.from_conn_string(DB_URI) as store:
    builder = StateGraph(...)
    graph = builder.compile(store=store)

Example: using Postgres store

pip install -U psycopg psycopg-pool langgraph langgraph-checkpoint-postgres

Setup

You need to call store.setup() the first time you're using Postgres store

SyncAsync

from langchain_core.runnables import RunnableConfig
from langchain.chat_models import init_chat_model
from langgraph.graph import StateGraph, MessagesState, START
from langgraph.checkpoint.postgres import PostgresSaver
from langgraph.store.postgres import PostgresStore
from langgraph.store.base import BaseStore

model = init_chat_model(model="anthropic:claude-3-5-haiku-latest")

DB_URI = "postgresql://postgres:postgres@localhost:5442/postgres?sslmode=disable"

with (
    PostgresStore.from_conn_string(DB_URI) as store,
    PostgresSaver.from_conn_string(DB_URI) as checkpointer,
):
    # store.setup()
    # checkpointer.setup()

    def call_model(
        state: MessagesState,
        config: RunnableConfig,
        *,
        store: BaseStore,
    ):
        user_id = config["configurable"]["user_id"]
        namespace = ("memories", user_id)
        memories = store.search(namespace, query=str(state["messages"][-1].content))
        info = "\n".join([d.value["data"] for d in memories])
        system_msg = f"You are a helpful assistant talking to the user. User info: {info}"

        # Store new memories if the user asks the model to remember
        last_message = state["messages"][-1]
        if "remember" in last_message.content.lower():
            memory = "User name is Bob"
            store.put(namespace, str(uuid.uuid4()), {"data": memory})

        response = model.invoke(
            [{"role": "system", "content": system_msg}] + state["messages"]
        )
        return {"messages": response}

    builder = StateGraph(MessagesState)
    builder.add_node(call_model)
    builder.add_edge(START, "call_model")

    graph = builder.compile(
        checkpointer=checkpointer,
        store=store,
    )

    config = {
        "configurable": {
            "thread_id": "1",
            "user_id": "1",
        }
    }
    for chunk in graph.stream(
        {"messages": [{"role": "user", "content": "Hi! Remember: my name is Bob"}]},
        config,
        stream_mode="values",
    ):
        chunk["messages"][-1].pretty_print()

    config = {
        "configurable": {
            "thread_id": "2",
            "user_id": "1",
        }
    }

    for chunk in graph.stream(
        {"messages": [{"role": "user", "content": "what is my name?"}]},
        config,
        stream_mode="values",
    ):
        chunk["messages"][-1].pretty_print()

from langchain_core.runnables import RunnableConfig
from langchain.chat_models import init_chat_model
from langgraph.graph import StateGraph, MessagesState, START
from langgraph.checkpoint.postgres.aio import AsyncPostgresSaver
from langgraph.store.postgres.aio import AsyncPostgresStore
from langgraph.store.base import BaseStore

model = init_chat_model(model="anthropic:claude-3-5-haiku-latest")

DB_URI = "postgresql://postgres:postgres@localhost:5442/postgres?sslmode=disable"

async with (
    AsyncPostgresStore.from_conn_string(DB_URI) as store,
    AsyncPostgresSaver.from_conn_string(DB_URI) as checkpointer,
):
    # await store.setup()
    # await checkpointer.setup()

    async def call_model(
        state: MessagesState,
        config: RunnableConfig,
        *,
        store: BaseStore,
    ):
        user_id = config["configurable"]["user_id"]
        namespace = ("memories", user_id)
        memories = await store.asearch(namespace, query=str(state["messages"][-1].content))
        info = "\n".join([d.value["data"] for d in memories])
        system_msg = f"You are a helpful assistant talking to the user. User info: {info}"

        # Store new memories if the user asks the model to remember
        last_message = state["messages"][-1]
        if "remember" in last_message.content.lower():
            memory = "User name is Bob"
            await store.aput(namespace, str(uuid.uuid4()), {"data": memory})

        response = await model.ainvoke(
            [{"role": "system", "content": system_msg}] + state["messages"]
        )
        return {"messages": response}

    builder = StateGraph(MessagesState)
    builder.add_node(call_model)
    builder.add_edge(START, "call_model")

    graph = builder.compile(
        checkpointer=checkpointer,
        store=store,
    )

    config = {
        "configurable": {
            "thread_id": "1",
            "user_id": "1",
        }
    }
    async for chunk in graph.astream(
        {"messages": [{"role": "user", "content": "Hi! Remember: my name is Bob"}]},
        config,
        stream_mode="values",
    ):
        chunk["messages"][-1].pretty_print()

    config = {
        "configurable": {
            "thread_id": "2",
            "user_id": "1",
        }
    }

    async for chunk in graph.astream(
        {"messages": [{"role": "user", "content": "what is my name?"}]},
        config,
        stream_mode="values",
    ):
        chunk["messages"][-1].pretty_print()

Example: using Redis store

pip install -U langgraph langgraph-checkpoint-redis

Setup

You need to call store.setup() the first time you're using Redis store

SyncAsync

from langchain_core.runnables import RunnableConfig
from langchain.chat_models import init_chat_model
from langgraph.graph import StateGraph, MessagesState, START
from langgraph.checkpoint.redis import RedisSaver
from langgraph.store.redis import RedisStore
from langgraph.store.base import BaseStore

model = init_chat_model(model="anthropic:claude-3-5-haiku-latest")

DB_URI = "redis://localhost:6379"

with (
    RedisStore.from_conn_string(DB_URI) as store,
    RedisSaver.from_conn_string(DB_URI) as checkpointer,
):
    store.setup()
    checkpointer.setup()

    def call_model(
        state: MessagesState,
        config: RunnableConfig,
        *,
        store: BaseStore,
    ):
        user_id = config["configurable"]["user_id"]
        namespace = ("memories", user_id)
        memories = store.search(namespace, query=str(state["messages"][-1].content))
        info = "\n".join([d.value["data"] for d in memories])
        system_msg = f"You are a helpful assistant talking to the user. User info: {info}"

        # Store new memories if the user asks the model to remember
        last_message = state["messages"][-1]
        if "remember" in last_message.content.lower():
            memory = "User name is Bob"
            store.put(namespace, str(uuid.uuid4()), {"data": memory})

        response = model.invoke(
            [{"role": "system", "content": system_msg}] + state["messages"]
        )
        return {"messages": response}

    builder = StateGraph(MessagesState)
    builder.add_node(call_model)
    builder.add_edge(START, "call_model")

    graph = builder.compile(
        checkpointer=checkpointer,
        store=store,
    )

    config = {
        "configurable": {
            "thread_id": "1",
            "user_id": "1",
        }
    }
    for chunk in graph.stream(
        {"messages": [{"role": "user", "content": "Hi! Remember: my name is Bob"}]},
        config,
        stream_mode="values",
    ):
        chunk["messages"][-1].pretty_print()

    config = {
        "configurable": {
            "thread_id": "2",
            "user_id": "1",
        }
    }

    for chunk in graph.stream(
        {"messages": [{"role": "user", "content": "what is my name?"}]},
        config,
        stream_mode="values",
    ):
        chunk["messages"][-1].pretty_print()

from langchain_core.runnables import RunnableConfig
from langchain.chat_models import init_chat_model
from langgraph.graph import StateGraph, MessagesState, START
from langgraph.checkpoint.redis.aio import AsyncRedisSaver
from langgraph.store.redis.aio import AsyncRedisStore
from langgraph.store.base import BaseStore

model = init_chat_model(model="anthropic:claude-3-5-haiku-latest")

DB_URI = "redis://localhost:6379"

async with (
    AsyncRedisStore.from_conn_string(DB_URI) as store,
    AsyncRedisSaver.from_conn_string(DB_URI) as checkpointer,
):
    # await store.setup()
    # await checkpointer.asetup()

    async def call_model(
        state: MessagesState,
        config: RunnableConfig,
        *,
        store: BaseStore,
    ):
        user_id = config["configurable"]["user_id"]
        namespace = ("memories", user_id)
        memories = await store.asearch(namespace, query=str(state["messages"][-1].content))
        info = "\n".join([d.value["data"] for d in memories])
        system_msg = f"You are a helpful assistant talking to the user. User info: {info}"

        # Store new memories if the user asks the model to remember
        last_message = state["messages"][-1]
        if "remember" in last_message.content.lower():
            memory = "User name is Bob"
            await store.aput(namespace, str(uuid.uuid4()), {"data": memory})

        response = await model.ainvoke(
            [{"role": "system", "content": system_msg}] + state["messages"]
        )
        return {"messages": response}

    builder = StateGraph(MessagesState)
    builder.add_node(call_model)
    builder.add_edge(START, "call_model")

    graph = builder.compile(
        checkpointer=checkpointer,
        store=store,
    )

    config = {
        "configurable": {
            "thread_id": "1",
            "user_id": "1",
        }
    }
    async for chunk in graph.astream(
        {"messages": [{"role": "user", "content": "Hi! Remember: my name is Bob"}]},
        config,
        stream_mode="values",
    ):
        chunk["messages"][-1].pretty_print()

    config = {
        "configurable": {
            "thread_id": "2",
            "user_id": "1",
        }
    }

    async for chunk in graph.astream(
        {"messages": [{"role": "user", "content": "what is my name?"}]},
        config,
        stream_mode="values",
    ):
        chunk["messages"][-1].pretty_print()  

Use semantic search

You can enable semantic search in your graph's memory store: this lets graph agent search for items in the store by semantic similarity.

^{API Reference: init_embeddings}

from langchain.embeddings import init_embeddings
from langgraph.store.memory import InMemoryStore

# Create store with semantic search enabled
embeddings = init_embeddings("openai:text-embedding-3-small")
store = InMemoryStore(
    index={
        "embed": embeddings,
        "dims": 1536,
    }
)

store.put(("user_123", "memories"), "1", {"text": "I love pizza"})
store.put(("user_123", "memories"), "2", {"text": "I am a plumber"})

items = store.search(
    ("user_123", "memories"), query="I'm hungry", limit=1
)

Long-term memory with semantic search

from typing import Optional

from langchain.embeddings import init_embeddings
from langchain.chat_models import init_chat_model
from langgraph.store.base import BaseStore
from langgraph.store.memory import InMemoryStore
from langgraph.graph import START, MessagesState, StateGraph

llm = init_chat_model("openai:gpt-4o-mini")

# Create store with semantic search enabled
embeddings = init_embeddings("openai:text-embedding-3-small")
store = InMemoryStore(
    index={
        "embed": embeddings,
        "dims": 1536,
    }
)

store.put(("user_123", "memories"), "1", {"text": "I love pizza"})
store.put(("user_123", "memories"), "2", {"text": "I am a plumber"})

def chat(state, *, store: BaseStore):
    # Search based on user's last message
    items = store.search(
        ("user_123", "memories"), query=state["messages"][-1].content, limit=2
    )
    memories = "\n".join(item.value["text"] for item in items)
    memories = f"## Memories of user\n{memories}" if memories else ""
    response = llm.invoke(
        [
            {"role": "system", "content": f"You are a helpful assistant.\n{memories}"},
            *state["messages"],
        ]
    )
    return {"messages": [response]}


builder = StateGraph(MessagesState)
builder.add_node(chat)
builder.add_edge(START, "chat")
graph = builder.compile(store=store)

for message, metadata in graph.stream(
    input={"messages": [{"role": "user", "content": "I'm hungry"}]},
    stream_mode="messages",
):
    print(message.content, end="")

See this guide for more information on how to use semantic search with LangGraph memory store.