Text generation

This page shows you how to send chat prompts to a Gemini model by usingthe Google Cloud console, REST API, and supported SDKs.

To learn how to add images and other media to your request, seeImage understanding.

For a list of languages supported by Gemini, seeLanguage support.

To explorethe generative AI models and APIs that are available on Vertex AI, go toModel Garden in the Google Cloud console.

Go to Model Garden

If you're looking for a way to use Gemini directly from your mobile andweb apps, see theFirebase AI Logic client SDKs forSwift, Android, Web, Flutter, and Unity apps.

Generate text

For testing and iterating on chat prompts, we recommend using theGoogle Cloud console. To send prompts programmatically to the model, you can use theREST API, Google Gen AI SDK, Vertex AI SDK for Python, or one of the other supported libraries andSDKs.

You can use system instructions to steer the behavior of the model based on aspecific need or use case. For example, you can define a persona or role for achatbot that responds to customer service requests. For more information, seethesystem instructions code samples.

You can use theGoogle Gen AI SDK to send requests ifyou're usingGemini 2.0 Flash.

Here is a simple text generation example.

Python

Install

pip install --upgrade google-genai

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI:

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values# with appropriate values for your project.exportGOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECTexportGOOGLE_CLOUD_LOCATION=globalexportGOOGLE_GENAI_USE_VERTEXAI=True

fromgoogleimportgenaifromgoogle.genai.typesimportHttpOptionsclient=genai.Client(http_options=HttpOptions(api_version="v1"))response=client.models.generate_content(model="gemini-2.5-flash",contents="How does AI work?",)print(response.text)# Example response:# Okay, let's break down how AI works. It's a broad field, so I'll focus on the ...## Here's a simplified overview:# ...

Go

Learn how to install or update theGo.

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI:

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values# with appropriate values for your project.exportGOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECTexportGOOGLE_CLOUD_LOCATION=globalexportGOOGLE_GENAI_USE_VERTEXAI=True

import("context""fmt""io""google.golang.org/genai")//generateWithTextshowshowtogeneratetextusingatextprompt.funcgenerateWithText(wio.Writer)error{ctx:=context.Background()client,err:=genai.NewClient(ctx, &genai.ClientConfig{HTTPOptions:genai.HTTPOptions{APIVersion:"v1"},})iferr!=nil{returnfmt.Errorf("failed to create genai client: %w",err)}resp,err:=client.Models.GenerateContent(ctx,"gemini-2.5-flash",genai.Text("How does AI work?"),nil,)iferr!=nil{returnfmt.Errorf("failed to generate content: %w",err)}respText:=resp.Text()fmt.Fprintln(w,respText)//Exampleresponse://That's a great question! Understanding how AI works can feel like ...//...//**1.TheFoundation:DataandAlgorithms**//...returnnil}

Node.js

Install

npm install @google/genai

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI:

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values# with appropriate values for your project.exportGOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECTexportGOOGLE_CLOUD_LOCATION=globalexportGOOGLE_GENAI_USE_VERTEXAI=True

const{GoogleGenAI}=require('@google/genai');constGOOGLE_CLOUD_PROJECT=process.env.GOOGLE_CLOUD_PROJECT;constGOOGLE_CLOUD_LOCATION=process.env.GOOGLE_CLOUD_LOCATION||'global';asyncfunctiongenerateContent(projectId=GOOGLE_CLOUD_PROJECT,location=GOOGLE_CLOUD_LOCATION){constclient=newGoogleGenAI({vertexai:true,project:projectId,location:location,});constresponse=awaitclient.models.generateContent({model:'gemini-3-flash-preview',contents:'How does AI work?',});console.log(response.text);returnresponse.text;}

Java

Learn how to install or update theJava.

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI:

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values# with appropriate values for your project.exportGOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECTexportGOOGLE_CLOUD_LOCATION=globalexportGOOGLE_GENAI_USE_VERTEXAI=True

importcom.google.genai.Client;importcom.google.genai.types.GenerateContentResponse;importcom.google.genai.types.HttpOptions;publicclassTextGenerationWithText{publicstaticvoidmain(String[]args){//TODO(developer):Replacethesevariablesbeforerunningthesample.StringmodelId="gemini-2.5-flash";generateContent(modelId);}//GeneratestextwithtextinputpublicstaticStringgenerateContent(StringmodelId){//Initializeclientthatwillbeusedtosendrequests.Thisclientonlyneedstobecreated//once,andcanbereusedformultiplerequests.try(Clientclient=Client.builder().location("global").vertexAI(true).httpOptions(HttpOptions.builder().apiVersion("v1").build()).build()){GenerateContentResponseresponse=client.models.generateContent(modelId,"How does AI work?",null);System.out.print(response.text());//Exampleresponse://Okay,let's break down how AI works. It'sabroadfield,soI'll focus on the ...////Here's a simplified overview://...returnresponse.text();}}}

C#

Learn how to install or update theC#.

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI:

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values# with appropriate values for your project.exportGOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECTexportGOOGLE_CLOUD_LOCATION=globalexportGOOGLE_GENAI_USE_VERTEXAI=True

usingGoogle.GenAI;usingGoogle.GenAI.Types;usingSystem;usingSystem.Threading.Tasks;publicclassTextGenWithTxt{publicasyncTask<string>GenerateContent(stringprojectId="your-project-id",stringlocation="global",stringmodel="gemini-2.5-flash"){awaitusingvarclient=newClient(project:projectId,location:location,vertexAI:true,httpOptions:newHttpOptions{ApiVersion="v1"});GenerateContentResponseresponse=awaitclient.Models.GenerateContentAsync(model:model,contents:"How does AI work?");stringresponseText=response.Candidates[0].Content.Parts[0].Text;Console.WriteLine(responseText);//Exampleresponse://AI,orArtificialIntelligence,atitscore,isaboutcreatingmachinesthatcanperform...//Here's a breakdown of how it generally works...returnresponseText;}}

Streaming and non-streaming responses

You can choose whether the model generatesstreaming responses ornon-streaming responses. For streaming responses, you receive each responseas soon as its output token is generated. For non-streaming responses, you receiveall responses after all of the output tokens are generated.

Here is a streaming text generation example.

Python

Before trying this sample, follow thePython setup instructions in theVertex AI quickstart using client libraries. For more information, see theVertex AIPython API reference documentation.

To authenticate to Vertex AI, set up Application Default Credentials. For more information, seeSet up authentication for a local development environment.

fromgoogleimportgenaifromgoogle.genai.typesimportHttpOptionsclient=genai.Client(http_options=HttpOptions(api_version="v1"))chat_session=client.chats.create(model="gemini-2.5-flash")forchunkinchat_session.send_message_stream("Why is the sky blue?"):print(chunk.text,end="")# Example response:# The#  sky appears blue due to a phenomenon called **Rayleigh scattering**. Here's#  a breakdown of why:# ...

Gemini multiturn chat behavior

When you use multiturn chat, Vertex AI locally stores the initial contentand prompts that you sent to the model. Vertex AI sends all of this data witheach subsequent request to the model. Consequently, the input costs for eachmessage that you send is a running total of all the data that was already sentto the model. If your initial content is sufficiently large, consider usingcontext caching when you create the initial model object to bettercontrol input costs.

What's next

Except as otherwise noted, the content of this page is licensed under theCreative Commons Attribution 4.0 License, and code samples are licensed under theApache 2.0 License. For details, see theGoogle Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.

Last updated 2026-02-19 UTC.