> ## Documentation Index
> Fetch the complete documentation index at: https://docs.langchain.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Retriever integrations

> Integrate with retrievers using LangChain Python.

A [retriever](/oss/python/langchain/retrieval#building-blocks) is an interface that returns documents given an unstructured query.
It is more general than a vector store.
A retriever does not need to be able to store documents, only to return (or retrieve) them.
Retrievers can be created from vector stores, but are also broad enough to include [Wikipedia search](/oss/python/integrations/retrievers/wikipedia/) and [Amazon Kendra](/oss/python/integrations/retrievers/amazon_kendra_retriever/).

Retrievers accept a string query as input and return a list of [`Document`](https://reference.langchain.com/python/langchain-core/documents/base/Document) objects as output.

Note that all [vector stores](/oss/python/integrations/vectorstores) can be cast to retrievers. Refer to the vector store [integration docs](/oss/python/integrations/vectorstores/) for available vector stores.
This page lists custom retrievers, implemented via subclassing BaseRetriever.

## Bring-your-own documents

The below retrievers allow you to index and search a custom corpus of documents.

| Retriever                                                                                | Self-host | Cloud offering | Package                                                                                                                                    |
| ---------------------------------------------------------------------------------------- | --------- | -------------- | ------------------------------------------------------------------------------------------------------------------------------------------ |
| [`AmazonKnowledgeBasesRetriever`](/oss/python/integrations/retrievers/bedrock)           | ❌         | ✅              | [`langchain-aws`](https://reference.langchain.com/python/langchain-aws/retrievers/bedrock/AmazonKnowledgeBasesRetriever)                   |
| [`AzureAISearchRetriever`](/oss/python/integrations/retrievers/azure_ai_search)          | ❌         | ✅              | [`langchain-community`](https://reference.langchain.com/python/langchain-community/retrievers/azure_ai_search/AzureAISearchRetriever)      |
| [`ElasticsearchRetriever`](/oss/python/integrations/retrievers/elasticsearch_retriever)  | ✅         | ✅              | [`langchain-elasticsearch`](https://reference.langchain.com/python/langchain-elasticsearch/retrievers/ElasticsearchRetriever)              |
| [`NVIDIARAGRetriever`](/oss/python/integrations/retrievers/nvidia)                       | ✅         | ❌              | [`langchain-nvidia-ai-endpoints`](https://reference.langchain.com/python/langchain-nvidia-ai-endpoints/retrievers/NVIDIARAGRetriever)      |
| [`VertexAISearchRetriever`](/oss/python/integrations/retrievers/google_vertex_ai_search) | ❌         | ✅              | [`langchain-google-community`](https://reference.langchain.com/python/langchain-google-community/vertex_ai_search/VertexAISearchRetriever) |

## External index

The below retrievers will search over an external index (e.g., constructed from Internet data or similar).

| Retriever                                                                            | Source                                                                                             | Package                                                                                                                                   |
| ------------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------- |
| [`ArxivRetriever`](/oss/python/integrations/retrievers/arxiv)                        | Scholarly articles on [arxiv.org](https://arxiv.org/)                                              | [`langchain-community`](https://reference.langchain.com/python/langchain-community/retrievers/arxiv/ArxivRetriever)                       |
| [`ParallelSearchRetriever`](/oss/python/integrations/retrievers/parallel)            | Internet search via the [Parallel Search API](https://docs.parallel.ai/search/search-quickstart)   | [`langchain-parallel`](https://reference.langchain.com/python/langchain-parallel/retrievers/ParallelSearchRetriever)                      |
| [`PerplexitySearchRetriever`](/oss/python/integrations/retrievers/perplexity_search) | Internet search via the [Perplexity Search API](https://docs.perplexity.ai/docs/search/quickstart) | [`langchain-perplexity`](https://reference.langchain.com/python/langchain-perplexity/retrievers/PerplexitySearchRetriever)                |
| [`TavilySearchAPIRetriever`](/oss/python/integrations/retrievers/tavily)             | Internet search                                                                                    | [`langchain-community`](https://reference.langchain.com/python/langchain-community/retrievers/tavily_search_api/TavilySearchAPIRetriever) |
| [`WikipediaRetriever`](/oss/python/integrations/retrievers/wikipedia)                | [Wikipedia](https://www.wikipedia.org/) articles                                                   | [`langchain-community`](https://reference.langchain.com/python/langchain-community/retrievers/wikipedia/WikipediaRetriever)               |

## All retrievers

<Columns cols={3}>
  <Card title="Activeloop Deep Memory" icon="link" href="/oss/python/integrations/retrievers/activeloop" arrow="true" cta="View guide" />

  <Card title="Amazon Kendra" icon="link" href="/oss/python/integrations/retrievers/amazon_kendra_retriever" arrow="true" cta="View guide" />

  <Card title="Arcee" icon="link" href="/oss/python/integrations/retrievers/arcee" arrow="true" cta="View guide" />

  <Card title="Arxiv" icon="link" href="/oss/python/integrations/retrievers/arxiv" arrow="true" cta="View guide" />

  <Card title="AskNews" icon="link" href="/oss/python/integrations/retrievers/asknews" arrow="true" cta="View guide" />

  <Card title="Azure AI Search" icon="link" href="/oss/python/integrations/retrievers/azure_ai_search" arrow="true" cta="View guide" />

  <Card title="Bedrock (Knowledge Bases)" icon="link" href="/oss/python/integrations/retrievers/bedrock" arrow="true" cta="View guide" />

  <Card title="BM25" icon="link" href="/oss/python/integrations/retrievers/bm25" arrow="true" cta="View guide" />

  <Card title="Box" icon="link" href="/oss/python/integrations/retrievers/box" arrow="true" cta="View guide" />

  <Card title="BREEBS (Open Knowledge)" icon="link" href="/oss/python/integrations/retrievers/breebs" arrow="true" cta="View guide" />

  <Card title="Chaindesk" icon="link" href="/oss/python/integrations/retrievers/chaindesk" arrow="true" cta="View guide" />

  <Card title="ChatGPT plugin" icon="link" href="/oss/python/integrations/retrievers/chatgpt-plugin" arrow="true" cta="View guide" />

  <Card title="Cognee" icon="link" href="/oss/python/integrations/retrievers/cognee" arrow="true" cta="View guide" />

  <Card title="Cohere reranker" icon="link" href="/oss/python/integrations/retrievers/cohere-reranker" arrow="true" cta="View guide" />

  <Card title="Cohere RAG" icon="link" href="/oss/python/integrations/retrievers/cohere" arrow="true" cta="View guide" />

  <Card title="Contextual AI Reranker" icon="link" href="/oss/python/integrations/retrievers/contextual" arrow="true" cta="View guide" />

  <Card title="Dappier" icon="link" href="/oss/python/integrations/retrievers/dappier" arrow="true" cta="View guide" />

  <Card title="DocArray" icon="link" href="/oss/python/integrations/retrievers/docarray_retriever" arrow="true" cta="View guide" />

  <Card title="Dria" icon="link" href="/oss/python/integrations/retrievers/dria_index" arrow="true" cta="View guide" />

  <Card title="ElasticSearch BM25" icon="link" href="/oss/python/integrations/retrievers/elastic_search_bm25" arrow="true" cta="View guide" />

  <Card title="Elasticsearch" icon="link" href="/oss/python/integrations/retrievers/elasticsearch_retriever" arrow="true" cta="View guide" />

  <Card title="Egnyte" icon="link" href="/oss/python/integrations/retrievers/egnyte" arrow="true" cta="View guide" />

  <Card title="Embedchain" icon="link" href="/oss/python/integrations/retrievers/embedchain" arrow="true" cta="View guide" />

  <Card title="FlashRank reranker" icon="link" href="/oss/python/integrations/retrievers/flashrank-reranker" arrow="true" cta="View guide" />

  <Card title="Fleet AI Context" icon="link" href="/oss/python/integrations/retrievers/fleet_context" arrow="true" cta="View guide" />

  <Card title="Galaxia" icon="link" href="/oss/python/integrations/retrievers/galaxia-retriever" arrow="true" cta="View guide" />

  <Card title="Google Drive" icon="link" href="/oss/python/integrations/retrievers/google_drive" arrow="true" cta="View guide" />

  <Card title="Google Vertex AI Search" icon="link" href="/oss/python/integrations/retrievers/google_vertex_ai_search" arrow="true" cta="View guide" />

  <Card title="Graph RAG" icon="link" href="/oss/python/integrations/retrievers/graph_rag" arrow="true" cta="View guide" />

  <Card title="GreenNode" icon="link" href="/oss/python/integrations/retrievers/greennode_reranker" arrow="true" cta="View guide" />

  <Card title="IBM watsonx.ai" icon="link" href="/oss/python/integrations/retrievers/ibm_watsonx_ranker" arrow="true" cta="View guide" />

  <Card title="JaguarDB Vector Database" icon="link" href="/oss/python/integrations/retrievers/jaguar" arrow="true" cta="View guide" />

  <Card title="Kay.ai" icon="link" href="/oss/python/integrations/retrievers/kay" arrow="true" cta="View guide" />

  <Card title="Kinetica Vectorstore" icon="link" href="/oss/python/integrations/retrievers/kinetica" arrow="true" cta="View guide" />

  <Card title="kNN" icon="link" href="/oss/python/integrations/retrievers/knn" arrow="true" cta="View guide" />

  <Card title="LinkupSearchRetriever" icon="link" href="/oss/python/integrations/retrievers/linkup_search" arrow="true" cta="View guide" />

  <Card title="LLMLingua Document Compressor" icon="link" href="/oss/python/integrations/retrievers/llmlingua" arrow="true" cta="View guide" />

  <Card title="LOTR (Merger Retriever)" icon="link" href="/oss/python/integrations/retrievers/merger_retriever" arrow="true" cta="View guide" />

  <Card title="Metal" icon="link" href="/oss/python/integrations/retrievers/metal" arrow="true" cta="View guide" />

  <Card title="NanoPQ (Product Quantization)" icon="link" href="/oss/python/integrations/retrievers/nanopq" arrow="true" cta="View guide" />

  <Card title="Nebius" icon="link" href="/oss/python/integrations/retrievers/nebius" arrow="true" cta="View guide" />

  <Card title="needle" icon="link" href="/oss/python/integrations/retrievers/needle" arrow="true" cta="View guide" />

  <Card title="Nimble Extract" icon="link" href="/oss/python/integrations/retrievers/nimble_extract" arrow="true" cta="View guide" />

  <Card title="Nimble Search" icon="link" href="/oss/python/integrations/retrievers/nimble_search" arrow="true" cta="View guide" />

  <Card title="NVIDIA RAG Blueprint" icon="link" href="/oss/python/integrations/retrievers/nvidia" arrow="true" cta="View guide" />

  <Card title="Outline" icon="link" href="/oss/python/integrations/retrievers/outline" arrow="true" cta="View guide" />

  <Card title="Parallel Search" icon="link" href="/oss/python/integrations/retrievers/parallel" arrow="true" cta="View guide" />

  <Card title="Permit" icon="link" href="/oss/python/integrations/retrievers/permit" arrow="true" cta="View guide" />

  <Card title="Perplexity Search" icon="link" href="/oss/python/integrations/retrievers/perplexity_search" arrow="true" cta="View guide" />

  <Card title="Pinecone Hybrid Search" icon="link" href="/oss/python/integrations/retrievers/pinecone_hybrid_search" arrow="true" cta="View guide" />

  <Card title="Pinecone Rerank" icon="link" href="/oss/python/integrations/retrievers/pinecone_rerank" arrow="true" cta="View guide" />

  <Card title="PubMed" icon="link" href="/oss/python/integrations/retrievers/pubmed" arrow="true" cta="View guide" />

  <Card title="Qdrant Sparse Vector" icon="link" href="/oss/python/integrations/retrievers/qdrant-sparse" arrow="true" cta="View guide" />

  <Card title="RAGatouille" icon="link" href="/oss/python/integrations/retrievers/ragatouille" arrow="true" cta="View guide" />

  <Card title="RePhraseQuery" icon="link" href="/oss/python/integrations/retrievers/re_phrase" arrow="true" cta="View guide" />

  <Card title="Rememberizer" icon="link" href="/oss/python/integrations/retrievers/rememberizer" arrow="true" cta="View guide" />

  <Card title="SEC filing" icon="link" href="/oss/python/integrations/retrievers/sec_filings" arrow="true" cta="View guide" />

  <Card title="SpiceDB" icon="link" href="/oss/python/integrations/retrievers/spicedb" arrow="true" cta="View guide" />

  <Card title="SVM" icon="link" href="/oss/python/integrations/retrievers/svm" arrow="true" cta="View guide" />

  <Card title="TavilySearchAPI" icon="link" href="/oss/python/integrations/retrievers/tavily" arrow="true" cta="View guide" />

  <Card title="TF-IDF" icon="link" href="/oss/python/integrations/retrievers/tf_idf" arrow="true" cta="View guide" />

  <Card title="NeuralDB" icon="link" href="/oss/python/integrations/retrievers/thirdai_neuraldb" arrow="true" cta="View guide" />

  <Card title="ValyuContext" icon="link" href="/oss/python/integrations/retrievers/valyu" arrow="true" cta="View guide" />

  <Card title="Vectorize" icon="link" href="/oss/python/integrations/retrievers/vectorize" arrow="true" cta="View guide" />

  <Card title="Vespa" icon="link" href="/oss/python/integrations/retrievers/vespa" arrow="true" cta="View guide" />

  <Card title="Wikipedia" icon="link" href="/oss/python/integrations/retrievers/wikipedia" arrow="true" cta="View guide" />

  <Card title="You.com" icon="link" href="/oss/python/integrations/retrievers/you-retriever" arrow="true" cta="View guide" />

  <Card title="Zep Cloud" icon="link" href="/oss/python/integrations/retrievers/zep_cloud_memorystore" arrow="true" cta="View guide" />

  <Card title="Zep Open Source" icon="link" href="/oss/python/integrations/retrievers/zep_memorystore" arrow="true" cta="View guide" />

  <Card title="Zotero" icon="link" href="/oss/python/integrations/retrievers/zotero" arrow="true" cta="View guide" />
</Columns>

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