Code beginner · 3 min read

How to build an AI chatbot in Python

Q: How to build an AI chatbot in Python

Use the openai Python SDK v1 to create a chatbot by initializing the client with your API key, sending user messages to client.chat.completions.create, and extracting the response from choices[0].message.content.

Direct answer

Use the openai Python SDK v1 to create a chatbot by initializing the client with your API key, sending user messages to client.chat.completions.create, and extracting the response from choices[0].message.content.

Setup

Install

bash

pip install openai

Env vars

OPENAI_API_KEY

Imports

python

import os
from openai import OpenAI

Examples

inHello, who are you?

outI am an AI chatbot here to assist you.

inCan you help me write Python code?

outAbsolutely! What kind of Python code do you need help with?

inTell me a joke.

outWhy did the programmer quit his job? Because he didn't get arrays.

Integration steps

Install the OpenAI Python SDK and set your API key in the environment variable OPENAI_API_KEY.
Import OpenAI and initialize the client with the API key from os.environ.
Build a messages list with user input as {"role": "user", "content": "..."}.
Call client.chat.completions.create with the model gpt-4o and the messages list.
Extract the chatbot reply from response.choices[0].message.content and display it.

Full code

python

import os
from openai import OpenAI

def main():
    # Initialize OpenAI client with API key from environment
    client = OpenAI(api_key=os.environ["OPENAI_API_KEY"])

    print("AI Chatbot (type 'exit' to quit)")
    while True:
        user_input = input("You: ")
        if user_input.lower() == "exit":
            print("Goodbye!")
            break

        messages = [{"role": "user", "content": user_input}]

        response = client.chat.completions.create(
            model="gpt-4o",
            messages=messages
        )

        reply = response.choices[0].message.content
        print(f"Bot: {reply}")

if __name__ == "__main__":
    main()

output

AI Chatbot (type 'exit' to quit)
You: Hello, who are you?
Bot: I am an AI chatbot here to assist you.
You: Tell me a joke.
Bot: Why did the programmer quit his job? Because he didn't get arrays.
You: exit
Goodbye!

API trace

Request

json

{"model": "gpt-4o", "messages": [{"role": "user", "content": "Hello, who are you?"}]}

Response

json

{"choices": [{"message": {"content": "I am an AI chatbot here to assist you."}}], "usage": {"total_tokens": 20}}

Extractresponse.choices[0].message.content

Variants

Streaming Chatbot ›

Use streaming to improve user experience with partial token outputs for longer responses.

python

import os
from openai import OpenAI

def main():
    client = OpenAI(api_key=os.environ["OPENAI_API_KEY"])

    print("AI Chatbot Streaming (type 'exit' to quit)")
    while True:
        user_input = input("You: ")
        if user_input.lower() == "exit":
            print("Goodbye!")
            break

        messages = [{"role": "user", "content": user_input}]

        stream = client.chat.completions.create(
            model="gpt-4o",
            messages=messages,
            stream=True
        )

        print("Bot: ", end="", flush=True)
        for chunk in stream:
            delta = chunk.choices[0].delta.content or ""
            print(delta, end="", flush=True)
        print()

if __name__ == "__main__":
    main()

Async Chatbot ›

Use async for integrating the chatbot into asynchronous applications or web servers.

python

import os
import asyncio
from openai import OpenAI

async def main():
    client = OpenAI(api_key=os.environ["OPENAI_API_KEY"])

    print("Async AI Chatbot (type 'exit' to quit)")
    while True:
        user_input = input("You: ")
        if user_input.lower() == "exit":
            print("Goodbye!")
            break

        messages = [{"role": "user", "content": user_input}]

        response = await client.chat.completions.create(
            model="gpt-4o",
            messages=messages
        )

        reply = response.choices[0].message.content
        print(f"Bot: {reply}")

if __name__ == "__main__":
    asyncio.run(main())

Using Anthropic Claude Model ›

Use Anthropic Claude for a strong alternative chatbot model with a different style and capabilities.

python

import os
from anthropic import Anthropic

def main():
    client = Anthropic(api_key=os.environ["ANTHROPIC_API_KEY"])

    print("Claude AI Chatbot (type 'exit' to quit)")
    while True:
        user_input = input("You: ")
        if user_input.lower() == "exit":
            print("Goodbye!")
            break

        response = client.messages.create(
            model="claude-3-5-sonnet-20241022",
            max_tokens=1024,
            system="You are a helpful assistant.",
            messages=[{"role": "user", "content": user_input}]
        )

        reply = response.content[0].text
        print(f"Bot: {reply}")

if __name__ == "__main__":
    main()

Performance

Latency~800ms for <code>gpt-4o</code> non-streaming response

Cost~$0.002 per 500 tokens exchanged with <code>gpt-4o</code>

Rate limitsTier 1: 500 requests per minute / 30,000 tokens per minute

Keep prompts concise to reduce token usage.
Use shorter model variants like <code>gpt-4o-mini</code> for cost savings.
Cache frequent responses to avoid repeated calls.

Approach	Latency	Cost/call	Best for
Standard Chat Completion	~800ms	~$0.002	Simple chatbot with full responses
Streaming Chat Completion	~800ms initial + streaming	~$0.002	Better UX for long answers
Async Chat Completion	~800ms	~$0.002	Integration in async apps or web servers

✓

Quick tip

Always manage your API keys securely via environment variables and avoid hardcoding them in your code.

⚠

Common mistake

Beginners often use deprecated SDK methods like <code>openai.ChatCompletion.create()</code> instead of the current <code>client.chat.completions.create()</code> pattern.

Verified 2026-04 · gpt-4o, gpt-4o-mini, claude-3-5-sonnet-20241022

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