Basic Chat Completion (Python)
from openai import OpenAI
client = OpenAI(api_key="YOUR_API_KEY")
response = client.chat.completions.create(
model="gpt-5",
messages=[
{"role": "system", "content": "You are a helpful assistant."},
{"role": "user", "content": "Explain what a context window is in one paragraph."}
]
)
print(response.choices[0].message.content)Streaming a Response
stream = client.chat.completions.create(
model="gpt-5",
messages=[{"role": "user", "content": "Write a short poem about the ocean."}],
stream=True
)
for chunk in stream:
if chunk.choices[0].delta.content:
print(chunk.choices[0].delta.content, end="")JavaScript / Node.js Example
import OpenAI from "openai";
const client = new OpenAI({ apiKey: "YOUR_API_KEY" });
const response = await client.chat.completions.create({
model: "gpt-5",
messages: [{ role: "user", content: "Summarize this in two sentences: ..." }],
});
console.log(response.choices[0].message.content);Common Parameters Worth Knowing
temperature controls randomness (lower is more focused and deterministic); max_tokens caps the length of the generated response; messages is the conversation history, including an optional system message that shapes overall behavior. See OpenAI's own current documentation for the complete, up-to-date parameter list and model names.
Related Pages
Frequently Asked
Is the model name in these examples always current?
Model names and versions change over time; check OpenAI's current documentation for the latest available model identifiers before deploying.
Do I need the official SDK to use these examples?
The official Python and JavaScript SDKs simplify usage significantly, as shown here; you can also call the API directly with raw HTTP requests if you prefer not to use an SDK.
Where do I get an API key?
Through your account on OpenAI's own platform; never commit a real API key to public source code or version control.
Where can I see similar examples for other providers?
See our Claude API Examples and Gemini API Examples pages for equivalent code in other major providers.