LangChain
An open-source framework for building LLM-powered applications in Python and JavaScript.
What is LangChain?
LangChain is the most-used Gen AI framework in 2026. It provides building blocks — chains, agents, tools, retrievers, memory — that let you assemble production LLM applications without reinventing the basics.
The framework had a rocky start (API churn through 2023) but stabilised. Most production Gen AI codebases at Indian startups have LangChain at their core, often paired with LangGraph for state management.
LangChain is not the only option — alternatives include Llama Index (data-focused), Semantic Kernel (Microsoft), and Haystack. But LangChain has the deepest ecosystem and is the default for Gen AI job postings.
Knowing LangChain is the price of entry for Gen AI engineering roles in India. Hiring panels assume you can use it.
An Indian SaaS company shipped a 50K-document RAG product in 6 weeks using LangChain. The team had no prior Gen AI experience but used LangChain's out-of-the-box retrieval chain to get to a working demo by week 2.
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