Quickstart

Baseten provides inference endpoints (Model APIs) that you can call directly, with no infrastructure to manage. Run popular open-source LLMs like DeepSeek V4 Pro, GLM 5.2, and Kimi K2.6 through APIs compatible with the OpenAI and Anthropic SDKs. For the full list, see supported models. Set your base URL, set your API key, and send a request to an LLM hosted on Baseten.

Set up your API key and SDK

Generate a personal API key from your Baseten account and install a client SDK to call models.

Export your API key

export BASETEN_API_KEY="paste-your-api-key-here"

setx BASETEN_API_KEY "paste-your-api-key-here"

Install a client SDK

uv pip install openai

npm install openai

Run inference

Every Model API works with the OpenAI SDK, with Anthropic SDK support in beta. Most also support tool calling, structured outputs, reasoning, and more. Call a model using the OpenAI SDK. This example uses zai-org/GLM-5.2, but you can swap in any supported model.

Python
JavaScript
cURL

Create a chat completion:

chat.py

from openai import OpenAI
import os

client = OpenAI(
    base_url="https://inference.baseten.co/v1",
    api_key=os.environ["BASETEN_API_KEY"],
)

response = client.chat.completions.create(
    model="zai-org/GLM-5.2",
    messages=[
        {"role": "user", "content": "What is inference in machine learning?"}
    ],
)

print(response.choices[0].message.content)

Create a chat completion:

chat.mjs

import OpenAI from "openai";

const client = new OpenAI({
    baseURL: "https://inference.baseten.co/v1",
    apiKey: process.env.BASETEN_API_KEY,
});

const response = await client.chat.completions.create({
    model: "zai-org/GLM-5.2",
    messages: [
        { role: "user", content: "What is inference in machine learning?" }
    ],
});

console.log(response.choices[0].message.content);

curl https://inference.baseten.co/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $BASETEN_API_KEY" \
  -d '{
    "model": "zai-org/GLM-5.2",
    "messages": [
      {"role": "user", "content": "What is inference in machine learning?"}
    ]
  }'

Success looks like this:

Inference in machine learning refers to the process of using a trained model
to make predictions or generate outputs from new input data...

Stream the response

Streaming returns tokens as the model generates them, so you see the first tokens immediately instead of waiting for the full reply. That responsiveness suits chat UIs and other interactive applications.

Python
JavaScript

Set stream=True to receive tokens as the model generates them:

stream.py

stream = client.chat.completions.create(
    model="zai-org/GLM-5.2",
    messages=[
        {"role": "user", "content": "Write a haiku about machine learning."}
    ],
    stream=True,
)

for chunk in stream:
    if not chunk.choices:
        continue
    content = chunk.choices[0].delta.content
    if content:
        print(content, end="")

Set stream: true to receive tokens as the model generates them:

stream.mjs

const stream = await client.chat.completions.create({
    model: "zai-org/GLM-5.2",
    messages: [
        { role: "user", content: "Write a haiku about machine learning." }
    ],
    stream: true,
});

for await (const chunk of stream) {
    const content = chunk.choices[0]?.delta?.content;
    if (content) process.stdout.write(content);
}

Explore Model API features

Structured outputs

Generate JSON that conforms to a schema you define.

Tool calling

Let the model invoke functions and use the results in its response.

Reasoning

Enable extended thinking for multi-step problem solving.

Next steps

Platform overview

Deploy models, run multi-step pipelines, train and fine-tune. See everything Baseten offers.

Deploy your first model

Go beyond Model APIs with a config-only Truss deployment on dedicated GPUs.

Get started

Model APIs

Inference

Training

Development

Deployment

Engines

Model Labs

Organization

Hosting options

Observability

Troubleshooting

Set up your API key and SDK

Run inference

Stream the response

Explore Model API features

Structured outputs

Tool calling

Reasoning

Next steps

Platform overview

Deploy your first model

​Set up your API key and SDK

​Run inference

​Stream the response

​Explore Model API features

Structured outputs

Tool calling

Reasoning

​Next steps

Platform overview

Deploy your first model

Set up your API key and SDK

Run inference

Stream the response

Explore Model API features

Next steps