LangChain Framework

LangChain is a Python and JavaScript framework for building applications with large language models. It provides abstractions for common patterns: prompts (templates + input variables), chains (sequences of LLM calls), memory (conversation history), agents (LLMs that decide which tools to use), and tool integration (web search, calculators, databases). Without LangChain, you'd manually manage prompts, parse LLM outputs, handle errors, and orchestrate workflows. LangChain standardizes these patterns. Most LLM applications built in 2024-2026 use LangChain or its competitors (LlamaIndex, Haystack).