Use Modellix LLM with the Vercel AI SDK

Use the Vercel AI SDK against the Modellix LLM gateway. Create an OpenAI Compatible provider with baseURL set to https://llm.modellix.ai/v1, then call generateText / streamText with Modellix provider/name model IDs.

This page covers LLM text only (https://llm.modellix.ai).Modellix model IDs are provider/name (for example openai/gpt-5.5). Pass that full string to the provider model factory. See Models & Pricing.

Set Up the AI SDK

Install Packages

npm install ai @ai-sdk/openai-compatible

For the alternate @ai-sdk/openai path below, also install @ai-sdk/openai. For Anthropic Messages, install @ai-sdk/anthropic.

Set Credentials

Create a Modellix API key in the console:

export MODELLIX_API_KEY="mdlx-xxxxxxxx"

Setting	Value
API key	Modellix API Key (`MODELLIX_API_KEY`)
`baseURL`	`https://llm.modellix.ai/v1` (include `/v1` for OpenAI-compatible providers)
Model	Exact Modellix Model ID (`provider/name`)

Use a Modellix key, not an OpenAI platform key. Do not point the AI SDK at the media host (https://api.modellix.ai).

Create an OpenAI Compatible Provider (Recommended)

Prefer @ai-sdk/openai-compatible for third-party gateways:

import { createOpenAICompatible } from "@ai-sdk/openai-compatible";
import { generateText } from "ai";

const modellix = createOpenAICompatible({
  name: "modellix",
  apiKey: process.env.MODELLIX_API_KEY,
  baseURL: "https://llm.modellix.ai/v1",
});

const { text } = await generateText({
  model: modellix("openai/gpt-5.5"),
  prompt: "Introduce yourself in one sentence",
});

console.log(text);

Swap the model string for any catalog ID (anthropic/claude-sonnet-5, google/gemini-3.6-flash, and so on). Traffic still uses Chat Completions on https://llm.modellix.ai/v1.

Optional: Streaming

import { streamText } from "ai";

const result = streamText({
  model: modellix("openai/gpt-5.5"),
  prompt: "Write a one-line haiku about APIs",
});

for await (const textPart of result.textStream) {
  process.stdout.write(textPart);
}

Optional: createOpenAI + Chat Completions

You can also customize @ai-sdk/openai. The default modellix("...") factory targets the Responses API. Modellix supports Responses, but for Chat Completions–only client code paths use .chat():

npm install @ai-sdk/openai

import { createOpenAI } from "@ai-sdk/openai";
import { generateText } from "ai";

const modellix = createOpenAI({
  apiKey: process.env.MODELLIX_API_KEY,
  baseURL: "https://llm.modellix.ai/v1",
  name: "modellix",
});

// Chat Completions
const chat = await generateText({
  model: modellix.chat("openai/gpt-5.5"),
  prompt: "ping",
});

// Responses (same host + /v1)
const responses = await generateText({
  model: modellix("openai/gpt-5.5"),
  prompt: "ping",
});

console.log(chat.text, responses.text);

See AI SDK OpenAI provider for baseURL and .chat() details.

Optional: Anthropic Provider (Messages)

For native Anthropic Messages instead of OpenAI-compatible Chat Completions:

npm install @ai-sdk/anthropic

import { createAnthropic } from "@ai-sdk/anthropic";
import { generateText } from "ai";

const modellix = createAnthropic({
  apiKey: process.env.MODELLIX_API_KEY,
  baseURL: "https://llm.modellix.ai", // no /v1
});

const { text } = await generateText({
  model: modellix("anthropic/claude-sonnet-5"),
  prompt: "Introduce yourself in one sentence",
});

Same host shape as the Anthropic SDK: no /v1 on baseURL. Most AI SDK apps should stay on createOpenAICompatible + /v1 unless you specifically need Messages.

Troubleshooting

Symptom	Check
401 Unauthorized	`MODELLIX_API_KEY` / `apiKey` is a valid Modellix key
404 / wrong path	OpenAI-compatible `baseURL` includes `/v1`; Anthropic `baseURL` does not
Model not found	Model is a full ID like `openai/gpt-5.5`, not bare `gpt-5.5`
Responses vs Chat errors	Use `createOpenAICompatible` or `createOpenAI(...).chat(...)` for Chat Completions
Still hitting OpenAI	Custom provider `baseURL` is Modellix, not the default OpenAI host

AI SDK — Providers and models — provider architecture
OpenAI Compatible providers — createOpenAICompatible
OpenAI provider — createOpenAI, .chat(), Responses
OpenAI SDK — same /v1 gateway without the AI SDK
LangChain — another Chat Completions client path
Models & Pricing — Model IDs and rates
LLM API guide — protocols and curl examples

Get Started

API

Agent

SDK

Framework

IDE

Tool

Use Modellix LLM with the Vercel AI SDK

Set Up the AI SDK

Troubleshooting

​Set Up the AI SDK

​Troubleshooting

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Set Up the AI SDK

Troubleshooting

Related