access Gemini and other generative AI models.
The Vertex AI service lets you use the Vertex AI API in Google Apps Script. This API gives you access to Gemini and other generative AI models for text generation, image generation, and more.
To get started with this advanced service, try the quickstart .
Prerequisites
-
A Google Cloud project with billing enabled. To check that an existing project has billing enabled, see Verify the billing status of your projects . To create a project and set up billing, see Create a Google Cloud project .
-
In the Google Cloud console, go to your Cloud project and enable the Vertex AI API:
-
In your Apps Script project, turn on the Vertex AI service. For steps, see Advanced Google services .
Reference
For more information about this service, see the Vertex AI API reference documentation . Like all advanced services in Apps Script, the Vertex AI service uses the same objects, methods, and parameters as the public API.
Sample code
The following sample code uses version 1 of the Vertex AI API.
Generate text
This sample code shows how to prompt the Gemini 2.5 Flash model to generate text. The function returns the output to Apps Script's execution log .
/**
* Main entry point to test the Vertex AI integration.
*/
function
main
()
{
const
prompt
=
'What is Apps Script in one sentence?'
;
try
{
const
response
=
callVertexAI
(
prompt
);
console
.
log
(
`Response:
${
response
}
`
);
}
catch
(
error
)
{
console
.
error
(
`Failed to call Vertex AI:
${
error
.
message
}
`
);
}
}
/**
* Calls the Vertex AI Gemini model.
*
* @param {string} prompt - The user's input prompt.
* @return {string} The text generated by the model.
*/
function
callVertexAI
(
prompt
)
{
// Configuration
const
projectId
=
' GOOGLE_CLOUD_PROJECT_ID
'
;
const
region
=
'us-central1'
;
const
modelName
=
'gemini-2.5-flash'
;
const
model
=
`projects/
${
projectId
}
/locations/
${
region
}
/publishers/google/models/
${
modelName
}
`
;
const
payload
=
{
contents
:
[{
role
:
'user'
,
parts
:
[{
text
:
prompt
}]
}],
generationConfig
:
{
temperature
:
0.1
,
maxOutputTokens
:
2048
}
};
// Execute the request using the Vertex AI Advanced Service
const
response
=
VertexAI
.
Endpoints
.
generateContent
(
payload
,
model
);
// Use optional chaining for safe property access
return
response
?
.
candidates
?
.[
0
]
?
.
content
?
.
parts
?
.[
0
]
?
.
text
||
'No response generated.'
;
}
Replace GOOGLE_CLOUD_PROJECT_ID
with the project ID
of your Cloud project.
Generate text using a service account
The following example shows how to generate text by authenticating as an Apps Script project using a service account .
/**
* Main entry point to test the Vertex AI integration.
*/
function
main
()
{
const
prompt
=
'What is Apps Script in one sentence?'
;
try
{
const
response
=
callVertexAI
(
prompt
);
console
.
log
(
`Response:
${
response
}
`
);
}
catch
(
error
)
{
console
.
error
(
`Failed to call Vertex AI:
${
error
.
message
}
`
);
}
}
/**
* Calls the Vertex AI Gemini model.
*
* @param {string} prompt - The user's input prompt.
* @return {string} The text generated by the model.
*/
function
callVertexAI
(
prompt
)
{
const
service
=
getServiceAccountService
();
// Configuration
const
projectId
=
' GOOGLE_CLOUD_PROJECT_ID
'
;
const
region
=
'us-central1'
;
const
modelName
=
'gemini-2.5-flash'
;
const
model
=
`projects/
${
projectId
}
/locations/
${
region
}
/publishers/google/models/
${
modelName
}
`
;
const
payload
=
{
contents
:
[{
role
:
'user'
,
parts
:
[{
text
:
prompt
}]
}],
generationConfig
:
{
temperature
:
0.1
,
maxOutputTokens
:
2048
}
};
// Execute the request using the Vertex AI Advanced Service
const
response
=
VertexAI
.
Endpoints
.
generateContent
(
payload
,
model
,
{},
// Authenticate with the service account token.
{
Authorization
:
`Bearer
${
service
.
getAccessToken
()
}
`
},
);
// Use optional chaining for safe property access
return
response
?
.
candidates
?
.[
0
]
?
.
content
?
.
parts
?
.[
0
]
?
.
text
||
'No response generated.'
;
}
/**
* Get a new OAuth2 service for a given service account.
*/
function
getServiceAccountService
()
{
const
serviceAccountKeyString
=
PropertiesService
.
getScriptProperties
().
getProperty
(
'SERVICE_ACCOUNT_KEY'
);
if
(
!
serviceAccountKeyString
)
{
throw
new
Error
(
'SERVICE_ACCOUNT_KEY property is not set. Please follow the setup instructions.'
);
}
const
serviceAccountKey
=
JSON
.
parse
(
serviceAccountKeyString
);
const
CLIENT_EMAIL
=
serviceAccountKey
.
client_email
;
const
PRIVATE_KEY
=
serviceAccountKey
.
private_key
;
const
SCOPES
=
[
'https://www.googleapis.com/auth/cloud-platform'
];
return
OAuth2
.
createService
(
'ServiceAccount'
)
.
setTokenUrl
(
'https://oauth2.googleapis.com/token'
)
.
setPrivateKey
(
PRIVATE_KEY
)
.
setIssuer
(
CLIENT_EMAIL
)
.
setPropertyStore
(
PropertiesService
.
getScriptProperties
())
.
setScope
(
SCOPES
);
}
