How to Use Google Service Accounts with Google Apps Script

Published in: Google Apps Script

This sample code shows how to use OAuth in Google Apps Script using Service Accounts. The G Suite admin can access the Google Drive files of any user - the username or email address of the user you are trying to impersonate specified with the method setSubject.

For this code to work, you need to create a Google Service account with domain-wide delegation, substitute the private key and client client email with the actual values and also add the Client Id to your Google Apps admin console with the Drive API Scope. The OAuth 2.0 access tokens are stored in the Script Properties.

var JSON = {
    "private_key": "Your Private Key",
    "client_email": "",
    "client_id": "1234567890",
    "user_email": ""

function getOAuthService(user) {
    return OAuth2.createService("Service Account")
        .setParam('access_type', 'offline')

function getUserFiles() {
    var service = getOAuthService();
    if (service.hasAccess()) {
        var url = '';
        var response = UrlFetchApp.fetch(url, {
            headers: {
                Authorization: 'Bearer ' + service.getAccessToken()

function reset() {
    var service = getOAuthService();

It is important to specify the user’s email on behalf of whom you wish to run this application else you’ll get a “Not Authorized to access this resource/api” error.

Also, if you are getting the 403 Insufficient permission error, it is likely because the application is request access to API scopes that are not authorized in the Google Apps admin console. The invalid_grant error is likely due to incorrect date and time settings of the server that is hosting the application.

📮  Subscribe to our Email Newsletter for Google tips and tutorials!
Published in: Google Apps Script

Looking for something? Find here!

Meet the Author

Web Geek, Google Developer Expert
Amit Agarwal

Amit Agarwal is a Google Developer Expert in Google Workspace and Google Apps Script. He holds an engineering degree in Computer Science (I.I.T.) and is the first professional blogger in India. He is the developer of Mail Merge for Gmail and Document Studio. Read more on Lifehacker and YourStory

Get in touch

Google Add-ons

Do more with your Gmail and GSuite account

We build bespoke solutions that use the capabilities and the features of Google Workspace for automating business processes and driving work productivity.

  1. Mail Merge with Attachments
    Send personalized email to your Google Contact with a Google Sheet and Gmail
  2. Save Emails and Attachments
    Download email messages and file attachments from Gmail to your Google Drive
  3. Google Forms Email Notifications
    Send email notifications to multiple people when a new Google Form is submitted
  4. Document Studio
    Create beautiful pixel perfect documents merging data from Google Sheets and Google Forms
  5. Creator Studio for Google Slides
    Turn your Google Slides presentations into animated GIFs and videos for uploading to YouTube