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theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/code_splitter/">How to split code</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/contextual_compression/">How to do retrieval with contextual compression</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/convert_runnable_to_tool/">How to convert Runnables to Tools</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/custom_callbacks/">How to create custom callback handlers</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/custom_chat_model/">How to create a custom chat model class</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/custom_embeddings/">Custom Embeddings</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/custom_llm/">How to create a custom LLM class</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/custom_retriever/">Custom Retriever</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/custom_tools/">How to create tools</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a 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theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/document_loader_markdown/">How to load Markdown</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/document_loader_office_file/">How to load Microsoft Office files</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/document_loader_pdf/">How to load PDFs</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/document_loader_web/">How to load web pages</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/dynamic_chain/">How to create a dynamic (self-constructing) chain</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/embed_text/">Text embedding models</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/ensemble_retriever/">How to combine results from multiple retrievers</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/example_selectors_langsmith/">How to select examples from a LangSmith dataset</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/example_selectors_length_based/">How to select examples by length</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/example_selectors_mmr/">How to select examples by maximal marginal relevance (MMR)</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/example_selectors_ngram/">How to select examples by n-gram overlap</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/example_selectors_similarity/">How to select examples by similarity</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/extraction_examples/">How to use reference examples when doing extraction</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" 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theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/indexing/">How to use the LangChain indexing API</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/inspect/">How to inspect runnables</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/lcel_cheatsheet/">LangChain Expression Language Cheatsheet</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/llm_caching/">How to cache LLM responses</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/llm_token_usage_tracking/">How to track token usage for LLMs</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/local_llms/">Run models locally</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/logprobs/">How to get log probabilities</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/long_context_reorder/">How to reorder retrieved results to mitigate the "lost in the middle" effect</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/markdown_header_metadata_splitter/">How to split Markdown by Headers</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/merge_message_runs/">How to merge consecutive messages of the same type</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/message_history/">How to add message history</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/migrate_agent/">How to migrate from legacy LangChain agents to LangGraph</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/multi_vector/">How to retrieve using multiple vectors per document</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/multimodal_inputs/">How to pass multimodal data 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class="menu__link" tabindex="0" href="/docs/how_to/output_parser_retry/">How to retry when a parsing error occurs</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/output_parser_string/">How to parse text from message objects</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/output_parser_xml/">How to parse XML output</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/output_parser_yaml/">How to parse YAML output</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/parent_document_retriever/">How to use the Parent Document Retriever</a></li><li 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tabindex="0" href="/docs/how_to/qa_sources/">How to get your RAG application to return sources</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/qa_streaming/">How to stream results from your RAG application</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/recursive_json_splitter/">How to split JSON data</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/recursive_text_splitter/">How to recursively split text by characters</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/how_to/response_metadata/">Response metadata</a></li><li 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string-out llms</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/concepts/text_splitters/">Text splitters</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/concepts/tokens/">Tokens</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/concepts/tool_calling/">Tool calling</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/concepts/tools/">Tools</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item hidden"><a class="menu__link" tabindex="0" href="/docs/concepts/tracing/">Tracing</a></li><li class="theme-doc-sidebar-item-link 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itemtype="https://schema.org/ListItem" class="breadcrumbs__item"><a class="breadcrumbs__link" itemprop="item" href="/docs/concepts/"><span itemprop="name">Conceptual guide</span></a><meta itemprop="position" content="1"></li><li itemscope="" itemprop="itemListElement" itemtype="https://schema.org/ListItem" class="breadcrumbs__item breadcrumbs__item--active"><span class="breadcrumbs__link" itemprop="name">Architecture</span><meta itemprop="position" content="2"></li></ul></nav><div class="tocCollapsible_ETCw theme-doc-toc-mobile tocMobile_ITEo"><button type="button" class="clean-btn tocCollapsibleButton_TO0P">On this page</button></div><div style="display:flex;flex-direction:column;align-items:flex-end;float:right;margin-left:12px"><a href="https://github.com/langchain-ai/langchain/blob/master/docs/docs/concepts/architecture.mdx" target="_blank"><img src="https://img.shields.io/badge/Open%20on%20GitHub-grey?logo=github&logoColor=white" alt="Open on GitHub"></a></div><div class="theme-doc-markdown markdown"><header><h1>Architecture</h1></header> <p>LangChain is a framework that consists of a number of packages.</p> <img src="/svg/langchain_stack_112024.svg" alt="Diagram outlining the hierarchical organization of the LangChain framework, displaying the interconnected parts across multiple layers." class="themedComponent_mlkZ themedComponent--light_NVdE" title="LangChain Framework Overview" style="width:100%"><img src="/svg/langchain_stack_112024_dark.svg" alt="Diagram outlining the hierarchical organization of the LangChain framework, displaying the interconnected parts across multiple layers." class="themedComponent_mlkZ themedComponent--dark_xIcU" title="LangChain Framework Overview" style="width:100%"> <h2 class="anchor anchorWithStickyNavbar_LWe7" id="langchain-core">langchain-core<a href="#langchain-core" class="hash-link" aria-label="Direct link to langchain-core" title="Direct link to langchain-core"></a></h2> <p>This package contains base abstractions for different components and ways to compose them together. The interfaces for core components like chat models, vector stores, tools and more are defined here. No third-party integrations are defined here. The dependencies are very lightweight.</p> <h2 class="anchor anchorWithStickyNavbar_LWe7" id="langchain">langchain<a href="#langchain" class="hash-link" aria-label="Direct link to langchain" title="Direct link to langchain"></a></h2> <p>The main <code>langchain</code> package contains chains and retrieval strategies that make up an application's cognitive architecture. These are NOT third-party integrations. All chains, agents, and retrieval strategies here are NOT specific to any one integration, but rather generic across all integrations.</p> <h2 class="anchor anchorWithStickyNavbar_LWe7" id="integration-packages">Integration packages<a href="#integration-packages" class="hash-link" aria-label="Direct link to Integration packages" title="Direct link to Integration packages"></a></h2> <p>Popular integrations have their own packages (e.g. <code>langchain-openai</code>, <code>langchain-anthropic</code>, etc) so that they can be properly versioned and appropriately lightweight.</p> <p>For more information see:</p> <ul> <li>A list <a href="/docs/integrations/providers/">integrations packages</a></li> <li>The <a href="https://python.langchain.com/api_reference/" target="_blank" rel="noopener noreferrer">API Reference</a> where you can find detailed information about each of the integration package.</li> </ul> <h2 class="anchor anchorWithStickyNavbar_LWe7" id="langchain-community">langchain-community<a href="#langchain-community" class="hash-link" aria-label="Direct link to langchain-community" title="Direct link to langchain-community"></a></h2> <p>This package contains third-party integrations that are maintained by the LangChain community. Key integration packages are separated out (see above). This contains integrations for various components (chat models, vector stores, tools, etc). All dependencies in this package are optional to keep the package as lightweight as possible.</p> <h2 class="anchor anchorWithStickyNavbar_LWe7" id="langgraph">langgraph<a href="#langgraph" class="hash-link" aria-label="Direct link to langgraph" title="Direct link to langgraph"></a></h2> <p><code>langgraph</code> is an extension of <code>langchain</code> aimed at building robust and stateful multi-actor applications with LLMs by modeling steps as edges and nodes in a graph.</p> <p>LangGraph exposes high level interfaces for creating common types of agents, as well as a low-level API for composing custom flows.</p> <div class="theme-admonition theme-admonition-info admonition_xJq3 alert alert--info"><div class="admonitionHeading_Gvgb"><span class="admonitionIcon_Rf37"><svg viewBox="0 0 14 16"><path fill-rule="evenodd" d="M7 2.3c3.14 0 5.7 2.56 5.7 5.7s-2.56 5.7-5.7 5.7A5.71 5.71 0 0 1 1.3 8c0-3.14 2.56-5.7 5.7-5.7zM7 1C3.14 1 0 4.14 0 8s3.14 7 7 7 7-3.14 7-7-3.14-7-7-7zm1 3H6v5h2V4zm0 6H6v2h2v-2z"></path></svg></span>Further reading</div><div class="admonitionContent_BuS1"><ul> <li>See our LangGraph overview <a href="https://langchain-ai.github.io/langgraph/concepts/high_level/#core-principles" target="_blank" rel="noopener noreferrer">here</a>.</li> <li>See our LangGraph Academy Course <a href="https://academy.langchain.com/courses/intro-to-langgraph" target="_blank" rel="noopener noreferrer">here</a>.</li> </ul></div></div> <h2 class="anchor anchorWithStickyNavbar_LWe7" id="langserve">langserve<a href="#langserve" class="hash-link" aria-label="Direct link to langserve" title="Direct link to langserve"></a></h2> <p>A package to deploy LangChain chains as REST APIs. Makes it easy to get a production ready API up and running.</p> <div class="theme-admonition theme-admonition-important admonition_xJq3 alert alert--info"><div class="admonitionHeading_Gvgb"><span class="admonitionIcon_Rf37"><svg viewBox="0 0 14 16"><path fill-rule="evenodd" d="M7 2.3c3.14 0 5.7 2.56 5.7 5.7s-2.56 5.7-5.7 5.7A5.71 5.71 0 0 1 1.3 8c0-3.14 2.56-5.7 5.7-5.7zM7 1C3.14 1 0 4.14 0 8s3.14 7 7 7 7-3.14 7-7-3.14-7-7-7zm1 3H6v5h2V4zm0 6H6v2h2v-2z"></path></svg></span>important</div><div class="admonitionContent_BuS1"><p>LangServe is designed to primarily deploy simple Runnables and work with well-known primitives in langchain-core.</p><p>If you need a deployment option for LangGraph, you should instead be looking at LangGraph Platform (beta) which will be better suited for deploying LangGraph applications.</p></div></div> <p>For more information, see the <a href="/docs/langserve/">LangServe documentation</a>.</p> <h2 class="anchor anchorWithStickyNavbar_LWe7" id="langsmith">LangSmith<a href="#langsmith" class="hash-link" aria-label="Direct link to LangSmith" title="Direct link to LangSmith"></a></h2> <p>A developer platform that lets you debug, test, evaluate, and monitor LLM applications.</p> <p>For more information, see the <a href="https://docs.smith.langchain.com" target="_blank" rel="noopener noreferrer">LangSmith documentation</a></p></div><footer class="theme-doc-footer docusaurus-mt-lg"><div class="row margin-top--sm theme-doc-footer-edit-meta-row"><div class="col"><a href="https://github.com/langchain-ai/langchain/edit/master/docs/docs/concepts/architecture.mdx" target="_blank" rel="noopener noreferrer" class="theme-edit-this-page"><svg fill="currentColor" height="20" width="20" viewBox="0 0 40 40" class="iconEdit_Z9Sw" aria-hidden="true"><g><path d="m34.5 11.7l-3 3.1-6.3-6.3 3.1-3q0.5-0.5 1.2-0.5t1.1 0.5l3.9 3.9q0.5 0.4 0.5 1.1t-0.5 1.2z m-29.5 17.1l18.4-18.5 6.3 6.3-18.4 18.4h-6.3v-6.2z"></path></g></svg>Edit this 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