Retrievers
A retriever 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 and Amazon Kendra.
Retrievers accept a string query as input and return a list of Documents as output.
For specifics on how to use retrievers, see the relevant how-to guides here.
Note that all vector stores can be cast to retrievers. Refer to the vector store integration docs 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.
External index
The below retrievers will search over an external index (e.g., constructed from Internet data or similar).
| Retriever | Source | Package |
|---|---|---|
| ArxivRetriever | Scholarly articles on arxiv.org | langchain_community |
| TavilySearchAPIRetriever | Internet search | langchain_community |
| WikipediaRetriever | Wikipedia articles | langchain_community |
All retrievers
| Name | Description |
|---|---|
| Activeloop Deep Memory | Activeloop Deep Memory is a suite of tools that enables you to optimi... |
| Amazon Kendra | Amazon Kendra is an intelligent search service provided by Amazon Web... |
| Arcee | Arcee helps with the development of the SLMs—small, specialized, secu... |
| Arxiv | arXiv is an open-access archive for 2 million scholarly articles in t... |
| AskNews | AskNews infuses any LLM with the latest global news (or historical ne... |
| Azure AI Search | Azure AI Search (formerly known as Azure Cognitive Search) is a Micro... |
| Bedrock (Knowledge Bases) | This guide will help you getting started with the AWS Knowledge Bases... |
| BM25 | BM25 (Wikipedia) also known as the Okapi BM25, is a ranking function ... |
| Box | This will help you getting started with the Box retriever. For detail... |
| BREEBS (Open Knowledge) | BREEBS is an open collaborative knowledge platform. |
| Chaindesk | Chaindesk platform brings data from anywhere (Datsources: Text, PDF, ... |
| ChatGPT plugin | OpenAI plugins connect ChatGPT to third-party applications. These plu... |
| Cohere reranker | Cohere is a Canadian startup that provides natural language processin... |
| Cohere RAG | Cohere is a Canadian startup that provides natural language processin... |
| Dappier | Dappier connects any LLM or your Agentic AI to real-time, rights-clea... |
| DocArray | DocArray is a versatile, open-source tool for managing your multi-mod... |
| Dria | Dria is a hub of public RAG models for developers to both contribute ... |
| ElasticSearch BM25 | Elasticsearch is a distributed, RESTful search and analytics engine. ... |
| Elasticsearch | Elasticsearch is a distributed, RESTful search and analytics engine. ... |
| Embedchain | Embedchain is a RAG framework to create data pipelines. It loads, ind... |
| FlashRank reranker | FlashRank is the Ultra-lite & Super-fast Python library to add re-ran... |
| Fleet AI Context | Fleet AI Context is a dataset of high-quality embeddings of the top 1... |
| Google Drive | This notebook covers how to retrieve documents from Google Drive. |
| Google Vertex AI Search | Google Vertex AI Search (formerly known as Enterprise Search on Gener... |
| IBM watsonx.ai | WatsonxRerank is a wrapper for IBM watsonx.ai foundation models. |
| JaguarDB Vector Database | [JaguarDB Vector Database](http://www.jaguardb.com/windex.html |
| Kay.ai | Kai Data API built for RAG 🕵️ We are curating the world's largest da... |
| Kinetica Vectorstore based Retriever | Kinetica is a database with integrated support for vector similarity ... |
| kNN | In statistics, the k-nearest neighbours algorithm (k-NN) is a non-par... |
| LinkupSearchRetriever | Linkup provides an API to connect LLMs to the web and the Linkup Prem... |
| LLMLingua Document Compressor | LLMLingua utilizes a compact, well-trained language model (e.g., GPT2... |
| LOTR (Merger Retriever) | Lord of the Retrievers (LOTR), also known as MergerRetriever, takes a... |
| Metal | Metal is a managed service for ML Embeddings. |
| Milvus Hybrid Search | Milvus is an open-source vector database built to power embedding sim... |
| NanoPQ (Product Quantization) | Product Quantization algorithm (k-NN) in brief is a quantization algo... |
| needle | Needle Retriever |
| Outline | Outline is an open-source collaborative knowledge base platform desig... |
| Pinecone Hybrid Search | Pinecone is a vector database with broad functionality. |
| PubMed | PubMed® by The National Center for Biotechnology Information, Nationa... |
| Qdrant Sparse Vector | Qdrant is an open-source, high-performance vector search engine/datab... |
| RAGatouille | RAGatouille makes it as simple as can be to use ColBERT! |
| RePhraseQuery | RePhraseQuery is a simple retriever that applies an LLM between the u... |
| Rememberizer | Rememberizer is a knowledge enhancement service for AI applications c... |
| SEC filing | SEC filing is a financial statement or other formal document submitte... |
| Self-querying retrievers | |
| SingleStoreDB | SingleStoreDB is a high-performance distributed SQL database that sup... |
| SVM | Support vector machines (SVMs) are a set of supervised learning metho... |
| TavilySearchAPI | Tavily's Search API is a search engine built specifically for AI agen... |
| TF-IDF | TF-IDF means term-frequency times inverse document-frequency. |
| **NeuralDB** | NeuralDB is a CPU-friendly and fine-tunable retrieval engine develope... |
| Vespa | Vespa is a fully featured search engine and vector database. It suppo... |
| Wikipedia | Overview |
| You.com | you.com API is a suite of tools designed to help developers ground th... |
| Zep Cloud | Retriever Example for Zep Cloud |
| Zep Open Source | Retriever Example for Zep |
| Zilliz Cloud Pipeline | Zilliz Cloud Pipelines transform your unstructured data to a searchab... |