Gemini API quickstart

This quickstart shows you how to install our libraries and make your first request, stream responses, build multi-turn conversations, and use tools using the standard generateContent method.

Before you begin

To use the Gemini API, you need to have an API key to authenticate your requests, enforce security limits, and track usage to your account.

Create one on AI Studio for free to get started:

Create a Gemini API Key

Install the Google GenAI SDK

Python

Using Python 3.9+, install the google-genai package using the following pip command:

pip install -q -U google-genai

JavaScript

Using Node.js v18+, install the Google Gen AI SDK for TypeScript and JavaScript using the following npm command:

npm install @google/genai

Generate text

Use the models.generate_content method to generate a text response.

Python

from google import genai

client = genai.Client()

response = client.models.generate_content(
    model="gemini-3.5-flash",
    contents="Explain how AI works in a few words"
)

print(response.text)

JavaScript

import { GoogleGenAI } from "@google/genai";

const ai = new GoogleGenAI({});

async function main() {
  const response = await ai.models.generateContent({
    model: "gemini-3.5-flash",
    contents: "Explain how AI works in a few words",
  });

  console.log(response.text);
}

main();

REST

curl "https://generativelanguage.googleapis.com/v1beta/models/gemini-3.5-flash:generateContent" \
  -H "x-goog-api-key: $GEMINI_API_KEY" \
  -H 'Content-Type: application/json' \
  -X POST \
  -d '{
    "contents": [
      {
        "parts": [
          {
            "text": "Explain how AI works in a few words"
          }
        ]
      }
    ]
  }'

Stream responses

By default, the model returns a response only after the entire generation process is complete. For a faster, more interactive experience, you can stream the response chunks as they are generated.

Python

response = client.models.generate_content_stream(
    model="gemini-3.5-flash",
    contents="Explain how AI works in detail"
)

for chunk in response:
    print(chunk.text, end="", flush=True)

JavaScript

async function main() {
  const responseStream = await ai.models.generateContentStream({
    model: "gemini-3.5-flash",
    contents: "Explain how AI works in detail",
  });

  for await (const chunk of responseStream) {
    process.stdout.write(chunk.text);
  }
}

main();

REST

curl "https://generativelanguage.googleapis.com/v1beta/models/gemini-3.5-flash:streamGenerateContent" \
  -H "x-goog-api-key: $GEMINI_API_KEY" \
  -H 'Content-Type: application/json' \
  --no-buffer \
  -X POST \
  -d '{
    "contents": [
      {
        "parts": [
          {
            "text": "Explain how AI works in detail"
          }
        ]
      }
    ]
  }'

Multi-turn conversations

For multi-turn conversations, the SDKs provide a stateful chats helper to build a multi-turn chat experience that automatically manages conversation history.

Python

chat = client.chats.create(model="gemini-3.5-flash")

response1 = chat.send_message("I have 2 dogs in my house.")
print("Response 1:", response1.text)

response2 = chat.send_message("How many paws are in my house?")
print("Response 2:", response2.text)

JavaScript

async function main() {
  const chat = ai.chats.create({ model: "gemini-3.5-flash" });

  let response = await chat.sendMessage({ message: "I have 2 dogs in my house." });
  console.log("Response 1:", response.text);

  response = await chat.sendMessage({ message: "How many paws are in my house?" });
  console.log("Response 2:", response.text);
}

main();

REST

# REST is stateless. You must pass the full conversation history in the request.
curl "https://generativelanguage.googleapis.com/v1beta/models/gemini-3.5-flash:generateContent" \
  -H "x-goog-api-key: $GEMINI_API_KEY" \
  -H 'Content-Type: application/json' \
  -X POST \
  -d '{
    "contents": [
      {
        "role": "user",
        "parts": [{"text": "I have 2 dogs in my house."}]
      },
      {
        "role": "model",
        "parts": [{"text": "That is nice! Two dogs mean you have plenty of company."}]
      },
      {
        "role": "user",
        "parts": [{"text": "How many paws are in my house?"}]
      }
    ]
  }'

Use tools

Extend the model's capabilities by grounding responses with Google Search to access real-time web content. The model automatically decides when to search, executes queries, and synthesizes a response.

Python

from google import genai
from google.genai import types

config = types.GenerateContentConfig(
    tools=[types.Tool(google_search=types.GoogleSearch())]
)

response = client.models.generate_content(
    model="gemini-3.5-flash",
    contents="Who won the euro 2024?",
    config=config
)

print(response.text)

metadata = response.candidates[0].grounding_metadata
if metadata.web_search_queries:
    print("\nSearch queries executed:")
    for query in metadata.web_search_queries:
        print(f" - {query}")

if metadata.grounding_chunks:
    print("\nSources:")
    for chunk in metadata.grounding_chunks:
        print(f" - [{chunk.web.title}]({chunk.web.uri})")

JavaScript

async function main() {
  const response = await ai.models.generateContent({
    model: "gemini-3.5-flash",
    contents: "Who won the euro 2024?",
    config: {
      tools: [{ googleSearch: {} }]
    }
  });

  console.log(response.text);

  const metadata = response.candidates[0]?.groundingMetadata;
  if (metadata?.webSearchQueries) {
    console.log("\nSearch queries executed:");
    for (const query of metadata.webSearchQueries) {
      console.log(` - ${query}`);
    }
  }
  if (metadata?.groundingChunks) {
    console.log("\nSources:");
    for (const chunk of metadata.groundingChunks) {
      console.log(` - [${chunk.web.title}](${chunk.web.uri})`);
    }
  }
}

main();

REST

curl "https://generativelanguage.googleapis.com/v1beta/models/gemini-3.5-flash:generateContent" \
  -H "x-goog-api-key: $GEMINI_API_KEY" \
  -H "Content-Type: application/json" \
  -X POST \
  -d '{
    "contents": [
      {
        "parts": [
          {"text": "Who won the euro 2024?"}
        ]
      }
    ],
    "tools": [
      {
        "google_search": {}
      }
    ]
  }'

The Gemini API also supports other built-in tools:

  • Code execution: Lets the model write and run Python code to solve complex math problems.
  • URL context: Lets you ground responses in specific web page URLs you provide.
  • File search: Lets you upload files and ground responses in their content using semantic search.
  • Google Maps: Lets you ground responses in location data and search for places, directions, and maps.
  • Computer use: Lets the model interact with a virtual computer screen, keyboard, and mouse to perform tasks.

Call custom functions

Use function calling to connect models to your custom tools and APIs. The model determines when to call your function and returns a functionCall in the response for your application to execute.

This example declares a mock temperature function and checks if the model wants to call it.

Python

from google import genai
from google.genai import types

weather_function = {
    "name": "get_current_temperature",
    "description": "Gets the current temperature for a given location.",
    "parameters": {
        "type": "object",
        "properties": {
            "location": {
                "type": "string",
                "description": "The city name, e.g. San Francisco",
            },
        },
        "required": ["location"],
    },
}

tools = types.Tool(function_declarations=[weather_function])
config = types.GenerateContentConfig(tools=[tools])

contents = ["What's the temperature in London?"]

response = client.models.generate_content(
    model="gemini-3.5-flash",
    contents=contents,
    config=config,
)

part = response.candidates[0].content.parts[0]
if part.function_call:
    fc = part.function_call
    print(f"Model requested function: {fc.name} with args {fc.args}")

    mock_result = {"temperature": "15C", "condition": "Cloudy"}

    contents.append(response.candidates[0].content)

    fn_response_part = types.Part.from_function_response(
        name=fc.name,
        response=mock_result,
        id=fc.id
    )
    contents.append(types.Content(role="user", parts=[fn_response_part]))

    final_response = client.models.generate_content(
        model="gemini-3.5-flash",
        contents=contents,
        config=config,
    )
    print("Final Response:", final_response.text)

JavaScript

import { GoogleGenAI, Type } from '@google/genai';

async function main() {
  const weatherFunction = {
    name: 'get_current_temperature',
    description: 'Gets the current temperature for a given location.',
    parameters: {
      type: Type.OBJECT,
      properties: {
        location: {
          type: Type.STRING,
          description: 'The city name, e.g. San Francisco',
        },
      },
      required: ['location'],
    },
  };

  const contents = [{
    role: 'user',
    parts: [{ text: "What's the temperature in London?" }]
  }];

  const response = await ai.models.generateContent({
    model: 'gemini-3.5-flash',
    contents: contents,
    config: {
      tools: [{ functionDeclarations: [weatherFunction] }],
    },
  });

  if (response.functionCalls && response.functionCalls.length > 0) {
    const fc = response.functionCalls[0];
    console.log(`Model requested function: ${fc.name}`);

    const mockResult = { temperature: "15C", condition: "Cloudy" };

    contents.push(response.candidates[0].content);

    contents.push({
      role: 'user',
      parts: [{
        functionResponse: {
          name: fc.name,
          response: mockResult,
          id: fc.id
        }
      }]
    });

    const finalResponse = await ai.models.generateContent({
      model: 'gemini-3.5-flash',
      contents: contents,
      config: {
        tools: [{ functionDeclarations: [weatherFunction] }],
      },
    });
    console.log("Final Response:", finalResponse.text);
  }
}

main();

REST

curl "https://generativelanguage.googleapis.com/v1beta/models/gemini-3.5-flash:generateContent" \
  -H "x-goog-api-key: $GEMINI_API_KEY" \
  -H 'Content-Type: application/json' \
  -X POST \
  -d '{
    "contents": [
      {
        "role": "user",
        "parts": [{"text": "What'\''s the temperature in London?"}]
      }
    ],
    "tools": [
      {
        "functionDeclarations": [
          {
            "name": "get_current_temperature",
            "description": "Gets the current temperature for a given location.",
            "parameters": {
              "type": "object",
              "properties": {
                "location": {
                  "type": "string",
                  "description": "The city name, e.g. San Francisco"
                }
              },
              "required": ["location"]
            }
          }
        ]
      }
    ]
  }'

What's next

Now that you've got started with the Gemini API, explore the following guides to build more advanced applications: