Use Meliai with LangChain for Sovereign AI Projects

LangChain’s ChatOpenAI class accepts a custom base_url, making Meliai a drop-in provider for any LangChain application. You keep every chain, agent, tool, and memory component exactly as-is — only the endpoint and API key change. Your data stays within the EU on every call.

Install LangChain

Install the langchain-openai package, which provides the ChatOpenAI and OpenAIEmbeddings classes used throughout this guide.

pip install langchain-openai

Configure ChatOpenAI with Meliai

Pass your Meliai API key and base URL when instantiating ChatOpenAI. Everything else — temperature, streaming, callbacks — works the same way.

import os
from langchain_openai import ChatOpenAI

llm = ChatOpenAI(
    model="<MODEL_ID>",
    api_key=os.environ["MELIAI_API_KEY"],
    base_url="https://api.meliai.ai/v1",
)

result = llm.invoke("What are the benefits of European data sovereignty?")
print(result.content)

Use in a chain

Compose your ChatOpenAI instance with prompts and other runnables using LangChain Expression Language (LCEL). No changes are needed compared to a standard OpenAI setup.

from langchain_core.prompts import ChatPromptTemplate

prompt = ChatPromptTemplate.from_messages([
    ("system", "You are a helpful assistant."),
    ("user", "{input}"),
])

chain = prompt | llm
result = chain.invoke({"input": "Name three open-weight LLMs."})
print(result.content)

Use embeddings

OpenAIEmbeddings accepts the same base_url parameter, giving you Meliai-hosted embedding models for vector search, RAG pipelines, and semantic similarity tasks.

from langchain_openai import OpenAIEmbeddings

embeddings = OpenAIEmbeddings(
    model="<EMBEDDING_MODEL_ID>",
    api_key=os.environ["MELIAI_API_KEY"],
    base_url="https://api.meliai.ai/v1",
)

vector = embeddings.embed_query("European AI infrastructure")

Append a routing suffix to any model ID to control how Meliai selects a provider. For example, use <MODEL_ID>:eco to prefer the lowest-carbon data center, or <MODEL_ID>:speed to prioritise the fastest available provider.