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Chat models are language models that use a sequence of messages as inputs and return messages as outputs .
While these LangChain classes support the indicated advanced feature, you may need to refer to provider-specific documentation to learn which hosted models or backends support the feature.
See the full list of chat model integrations below for more options.

Routers & proxies

Routers and proxies give you access to models from multiple providers through a single API and credential. They can simplify billing, let you switch between models without changing integrations, and offer features like automatic fallbacks.

Chat Completions API

Certain model providers offer endpoints that are compatible with OpenAI’s Chat Completions API. In such cases, you can use ChatOpenAI with a custom base_url to connect to these endpoints for basic chat functionality.
ChatOpenAI targets official OpenAI API specifications only. Non-standard response fields from third-party providers (e.g., reasoning_content, reasoning, reasoning_details) are not extracted or preserved. Use a provider-specific package when you need access to non-standard features.For instance, OpenRouter has a dedicated LangChain integration. See the ChatOpenRouter guide for setup and usage.

All chat models

If you’d like to contribute an integration, see Contributing integrations.