Frameworks and tools for building retrieval-augmented generation pipelines—document parsing, chunking, indexing, and query engines that connect LLMs to your data.
14 tools compared · Layer 2 · Updated April 29, 2026
Ranked by community traction, recent activity, and breadth of capabilities. Tap any tool for full pros, cons, pricing, and alternatives.
RAGFlow is Infiniflow's open-source RAG engine that fuses retrieval-augmented generation with agent capabilities to create a superior context layer for LLMs. With 78,300+ GitHub stars, it's one of the leading RAG-focused projects on GitHub and is widely used for enterprise knowledge bases, compliance-heavy industries, and research assistants.
+Best document parsing in the OSS RAG space — tables and OCR done right
Unstructured is the leading data-ingestion and transformation platform for AI applications. The open-source library and hosted Serverless API can ingest, parse, and stage 65+ file formats — PDFs, Word docs, HTML, spreadsheets, emails, images, and more — into clean structured JSON or markdown ready for RAG pipelines and LLM fine-tuning.
+Generous free tier — 15,000 pages on Serverless API with no expiration
LlamaIndex is a developer-focused platform providing comprehensive AI agent frameworks and document processing tools with modular components for building enterprise-grade document automation solutions. The platform enables organizations to transform unstructured documents into actionable intelligence through agentic OCR and AI workflows, with LlamaParse supporting 90+ file types and handling complex layouts, embedded images, multi-page tables, and handwritten content extraction. LlamaIndex offers an event-driven Workflows orchestration engine for multi-step AI processes with async-first architecture, alongside Python and TypeScript SDKs with pre-built connectors for LLMs, databases, and vector stores. The platform has processed over 500M+ documents with 25M+ monthly package downloads, serving 300k+ LlamaParse users including notable clients like Carlyle, Salesforce, and Rakuten.
+Comprehensive document support with 90+ file types including complex layouts and handwritten content
Haystack is an open-source AI orchestration framework developed by deepset GmbH for building production-ready agents and RAG (Retrieval-Augmented Generation) applications with emphasis on smart context engineering and transparent, modular AI system design. The framework provides full visibility into AI decision-making across retrieval, reasoning, memory, and tool use, with vendor-agnostic architecture supporting OpenAI, Anthropic, Mistral, Hugging Face, and various vector databases. Haystack offers advanced RAG pipelines with hybrid retrieval strategies, AI agents with standardized tool calling, multimodal AI capabilities, conversational AI, and content generation powered by Jinja2 templates for flexible prompt engineering. The platform is Kubernetes-ready with built-in reliability and observability features, offering unified tooling for moving from prototype to production with serializable, cloud-agnostic pipelines.
+Fully open-source and free to use with strong community support
Reducto is a Series B-funded AI document intelligence platform built by MIT engineers featuring state-of-the-art vision models that read documents like humans do, solving critical bottlenecks for AI teams working with unstructured data. The platform extracts structured data directly from documents with schema-level precision, handling invoice fields, onboarding forms, financial disclosures, and more across PDFs, images, spreadsheets, slides, and other formats through a single unified API. Since their Series A announcement, Reducto's monthly processing volume has grown by more than 6x, now processing close to a billion pages of data for leading technical teams including Harvey, Mercor, and Rogo, as well as enterprise clients including a Fortune 10 company, a Global Top 5 Hedge Fund, and category leaders across Healthcare, Insurance, and Real Estate. In July 2025, Reducto expanded beyond document reading with Reducto Edit for document generation capabilities.
+Exceptionally well-funded with $108M total raised, indicating strong investor confidence
Pathway is a high-performance Python ETL framework for stream processing, real-time analytics, LLM pipelines, and RAG. Rust engine processes millions of data points per second; uniquely mixes batch and streaming logic in the same workflow. Trusted by NATO and Intel; recently crossed 50K GitHub stars.
Carbon, acquired by Perplexity in December 2024, provided pre-built data connectors for ingesting unstructured data from 25+ sources into LLM applications. Its managed API was wound down in March 2025, with its technology now integrated into Perplexity's enterprise data connectivity stack. Carbon's connectors supported Google Drive, Notion, Slack, Confluence, and other popular data sources for RAG pipelines.
Vectara is a RAG-as-a-service platform that provides end-to-end retrieval-augmented generation through a single API. It handles document ingestion, chunking, embedding, retrieval, reranking, and generation—with built-in hallucination detection and citation extraction—without requiring developers to manage any RAG infrastructure.
Docling is IBM's open-source document conversion toolkit (Apache 2.0) that turns PDFs, DOCX, PPTX, and other formats into structured JSON or markdown using advanced layout analysis and table structure recognition. Now ships with Granite-Docling-258M — IBM's compact vision-language model purpose-built for accurate document conversion — and was donated to the Linux Foundation's Agentic AI Foundation in 2026.
Chunkr is a document parsing and chunking service optimized for RAG pipelines. It handles PDFs, images, tables, and complex document layouts, producing clean structured output ready for embedding and retrieval. Chunkr focuses on the critical pre-processing step that determines RAG quality.