{"slug": "building-a-legal-document-analyzer-in-typescript-with-nodejs", "title": "Building a Legal Document Analyzer in typescript with NodeJS", "summary": "A developer built a Legal Document Analyzer using HazelJS, a multi-agent framework, to automate parsing, term extraction, risk analysis, and obligation summarization of legal documents. The system uses a supervisor agent to coordinate specialist agents and RAG-powered document search for efficient retrieval.", "body_md": "Legal documents are notoriously complex, filled with specialized terminology, hidden risks, and critical obligations. Lawyers and legal professionals spend countless hours reviewing contracts, agreements, and other legal documents to identify key terms, assess risks, and summarize obligations. In this post, we'll build a Legal Document Analyzer using [HazelJS](https://hazeljs.ai/) that automates document parsing, term extraction, risk analysis, and obligation summarization.\n\nLegal document analysis presents several challenges:\n\nOur agent will address these challenges using HazelJS's multi-agent architecture, RAG-powered document search, and intelligent risk analysis.\n\nThe Legal Document Analyzer uses a multi-agent architecture where each agent specializes in a specific aspect of legal document analysis:\n\nThis separation allows each agent to focus on its specialty while the supervisor ensures smooth coordination between them.\n\nOne of the key features of our agent is the ability to search through a database of legal documents using Retrieval-Augmented Generation (RAG). We maintain a knowledge base of legal documents with metadata including:\n\nWhen a legal professional asks about a document, the DocumentParserAgent uses semantic search to find relevant documents based on their query. For example, a query like \"Find indemnification clauses in contracts\" would return documents containing indemnification provisions.\n\nThe RAG implementation uses HazelJS's `RAGPipeline`\n\nwith a `MemoryVectorStore`\n\nfor efficient semantic search:\n\n```\n@Service()\nexport class LegalKnowledgeBaseService {\n  private readonly embeddings = new LocalLegalEmbeddingProvider();\n  private readonly vectorStore = new MemoryVectorStore(this.embeddings);\n  private readonly rag = new RAGPipeline({\n    vectorStore: this.vectorStore,\n    embeddingProvider: this.embeddings,\n    topK: 3,\n  });\n\n  async answer(query: string, topK = 3) {\n    const sources = await this.search(query, topK);\n    return {\n      answer: sources.map((source) => source.content).join('\\n\\n'),\n      sources: sources.map((source) => ({\n        id: source.id,\n        score: Number(source.score.toFixed(3)),\n        category: source.metadata?.category,\n        riskType: source.metadata?.riskType,\n        severity: source.metadata?.severity,\n      })),\n    };\n  }\n}\n```\n\nThe DocumentParserAgent extracts structure and metadata from legal documents. It identifies:\n\nThis structured extraction provides a foundation for deeper analysis by other agents in the system.\n\nThe TermExtractorAgent identifies legal terms within documents and provides:\n\nThis helps legal professionals quickly understand specialized language and ensures consistent interpretation across documents.\n\nThe RiskAnalyzerAgent analyzes documents for potential risks and provides:\n\nThe agent calculates overall risk levels and provides comprehensive risk summaries, helping legal professionals prioritize their review efforts.\n\nThe ObligationSummarizerAgent extracts and organizes obligations from legal documents:\n\nThis systematic approach ensures that no obligations are overlooked and provides a clear roadmap for compliance.\n\nThe LegalManagerAgent uses HazelJS's supervisor routing to coordinate between the specialist agents. When a legal professional makes a request, the supervisor analyzes the request and routes it to the appropriate specialist:\n\nThe supervisor continues delegating until it has gathered enough information to provide a comprehensive legal analysis, then synthesizes the results into a cohesive report.\n\nDespite being a demo, the agent includes production-ready features:\n\nThe agent can be run with:\n\n```\nnpm install\nnpm run build\nnpm run dev\n```\n\nThe app runs on `http://localhost:3000`\n\nwith the HazelJS Inspector available at `/__hazel`\n\nfor real-time monitoring and debugging.\n\nYou can test the agent with a curl request:\n\n```\ncurl -s -X POST http://localhost:3000/legal/supervisor \\\n  -H 'content-type: application/json' \\\n  -d '{\"message\":\"Analyze this contract: Indemnification Clause: Party A agrees to indemnify and hold harmless Party B from any claims arising from negligence. Extract terms, analyze risks, and summarize obligations.\",\"userId\":\"legal-analyst-1\"}'\n```\n\nThe agent will analyze your request, parse the document, extract legal terms, identify risks, summarize obligations, and synthesize everything into a comprehensive legal analysis—all coordinated through the supervisor routing system.\n\nComplete Project: [Legal Document Analyzer](https://github.com/nisafatimaa/legal-document-analyzer)\n\nHazelJS Documentation: [Docs](https://hazeljs.ai/docs)\n\nThe Legal Document Analyzer demonstrates several key [HazelJS](https://hazeljs.ai/) capabilities:\n\nThis agent shows how HazelJS can be used to build professional applications that solve complex domain-specific challenges while maintaining production-grade quality and reliability. The multi-agent approach makes it easy to extend the system with additional specialists (like compliance checkers or jurisdiction analyzers) as needed.", "url": "https://wpnews.pro/news/building-a-legal-document-analyzer-in-typescript-with-nodejs", "canonical_source": "https://dev.to/nisa_fatima_bcd75fa085b76/building-a-legal-document-analyzer-in-typescript-with-nodejs-392p", "published_at": "2026-07-29 17:30:41+00:00", "updated_at": "2026-07-29 17:32:49.106772+00:00", "lang": "en", "topics": ["artificial-intelligence", "natural-language-processing", "ai-agents", "developer-tools"], "entities": ["HazelJS", "Legal Document Analyzer", "DocumentParserAgent", "TermExtractorAgent", "RiskAnalyzerAgent", "ObligationSummarizerAgent", "LegalManagerAgent", "LegalKnowledgeBaseService"], "alternates": {"html": "https://wpnews.pro/news/building-a-legal-document-analyzer-in-typescript-with-nodejs", "markdown": "https://wpnews.pro/news/building-a-legal-document-analyzer-in-typescript-with-nodejs.md", "text": "https://wpnews.pro/news/building-a-legal-document-analyzer-in-typescript-with-nodejs.txt", "jsonld": "https://wpnews.pro/news/building-a-legal-document-analyzer-in-typescript-with-nodejs.jsonld"}}