BirdNest Tech Talk

Oct 3, 2025 · Artificial Intelligence

How to Build Custom LLM and Chat Models in LangChain: A Step‑by‑Step Guide

This article explains why and how to create custom LLM and chat model wrappers in LangChain by inheriting base classes, implementing core methods like _call and _generate, and demonstrates a full example with an echo‑based chat model, including streaming support and testing benefits.