As developers and product teams, we understand the power of Gmail plugins in enhancing email productivity and workflows. When it comes to building these plugins, two main approaches emerge: Chrome extensions and Google Workspace Add-ons. Each approach offers distinct advantages and disadvantages, making the ideal choice dependent on your specific project requirements and priorities.

Chrome Extensions

Chrome extensions are small software programs that can be installed into the Google Chrome web browser to customize and enhance the browsing experience. They are essentially JavaScript/HTML code that runs in the context of a browser page in a sandbox with special access to Chrome browser API.


  • Unmatched Flexibility and Customization: Design a unique and dynamic UI that perfectly matches your vision and brand. With direct access to Gmail’s UI elements, extensions allow for seamless integration of additional functionalities within the familiar Gmail environment.
  • Faster Development: Leverage your existing JavaScript expertise and web development tools for quicker development compared to learning Apps Script.
  • Pre-built components and APIs: Utilize InboxSDK’s or Gmail.js’s pre-built components and APIs to streamline UI development and simplify interactions with Gmail data.


  • Non-native Look and Feel: The extension’s UI might not seamlessly integrate with Gmail’s native interface.
  • Security Considerations: Implement robust security measures to protect user data accessed by the extension.
  • Limited to Chromium-Based Browsers: Chrome extensions are not directly compatible with mobile applications, like Gmail mobile app.

Google Workspace Add-ons

Google Workspace Add-ons are mini-applications that integrate seamlessly with Google Workspace apps like Gmail, Calendar, Drive, and Docs. They enable developers to: extend functionality, improve workflow, enhance integration.


  • Native Look and Feel: Add-ons seamlessly integrate with Gmail’s interface, providing a familiar and consistent user experience.
  • Automatic Mobile Compatibility: Your add-on is available on the Gmail mobile app without additional development effort.
  • Calendar Support: Access and manipulate calendar data.


  • Server-Side Development: Add-ons are rendered by the server-side code, utilizing AppScript, which presents a significant shift for front-end developers accustomed to traditional web development practices.
  • Limited Client-Side Interaction: AppScript has limited capabilities for dynamic updates and user interaction on the client-side. So, the Add-on framework imposes constraints on UI design, potentially limiting creative freedom and achieving a truly immersive user experience.
  • Slower Asynchronous Communication: Changes to the UI are triggered by events and communicated back to the server for processing and subsequent updates. This introduces a delay between user actions and UI changes, requiring careful consideration for user experience.

Making the Case for Chrome Extensions

For projects requiring a highly customizable UI and complex/dynamic functionality, Chrome extensions present a compelling choice due to their:

  • Unmatched flexibility and customization: Utilize familiar web frameworks and libraries to design a unique and dynamic UI that perfectly matches your vision and user needs.
  • Minimal processing overhead: Compared to Google Workspace Add-ons, which rely on Google Apps Script (server-side event processing), Chrome extensions generally have lower processing overhead, leading to faster UI responsiveness.
  • Faster development: Leverage existing JavaScript expertise for quicker development compared to learning Apps Script.
  • Pre-built components and APIs: Utilize libraries like InboxSDK to accelerate UI development and unlock advanced features.
  • Code reusability: The core development process for Chrome extension-based Gmail plugins shares significant similarities with that of Outlook add-ins. Developers can greatly improve code reusability between these platforms.

While Google Workspace Add-ons offer a cross-platform solution with a native look and feel, their limitations in UI customization and functionality might hinder your ability to create a truly unique and powerful plugin. Therefore, if your primary goal is to build a Gmail plugin with a highly customizable, dynamic UI, and a rich set of features, Chrome extensions are the superior choice.

However, if you prioritize native look and feel, and automatic mobile compatibility, Google Workspace Add-ons can be a suitable alternative for simpler projects.

Building a Gmail Chrome Extension: Essential Components

When developing a Gmail Chrome extension, several key components are crucial for its functionality and security:

InboxSDK or Gmail.js
  • Purpose: Provides a powerful JavaScript library for interacting with Gmail data and functionalities within your extension.
  • Benefits:
    • Simplified UI development: Offers pre-built components and APIs for quickly and efficiently building UIs within Gmail.
    • Rich data access: Enables access to a wide range of Gmail data, including emails, threads, labels, contacts, and attachments.
    • Gmail UI manipulation: Allows control and interaction with various elements of the Gmail interface, like composing messages and adding labels.
Secure OAuth Flow
  • Purpose: Securely grants your extension access to a user’s Gmail data through Google’s OAuth 2.0 protocol.
  • Benefits:
    • User privacy and control: Users explicitly authorize your extension to access their data, ensuring privacy and control.
    • Enhanced security: Utilizes Google’s secure authentication infrastructure to protect user credentials and data.
    • Widely supported: Standard protocol used by various web applications, making integration easier.
User Session Management
  • Purpose: Manages user sessions and ensures proper authentication and authorization throughout the extension’s usage.
  • Benefits:
    • Maintains user context: Tracks and stores user information to provide a seamless experience across different sessions.
    • Prevents unauthorized access: Secures user data by invalidating tokens and sessions after a specific period of inactivity.
    • Improves user experience: Enables features like automatic login and personalized settings based on user information.
Third-Party API Gateway
  • Purpose: Streamlines communication with external APIs and services, enhances security, and aids in scaling your extension’s capabilities.
  • Benefits:
    • Centralized API management
    • Integration with various external services
    • Enhanced security and rate-limiting
    • Caching and performance optimization

Consider using Aurinko to streamline OAuth flow, user session management, and access to third-party APIs for your Chrome extension-based Gmail plugin. Aurinko is specifically designed as a backend for various Add-ins and Workspace apps, providing missing APIs. This can significantly streamline development and simplify the integration process.


Chrome extensions offer unparalleled flexibility, customization, and accelerated development while leveraging pre-built components and APIs. However, they might not seamlessly integrate with Gmail’s native interface and could pose security concerns. Conversely, Google Workspace Add-ons provide a native feel and automatic mobile compatibility but are limited by server-side development and constrained client-side interactions, potentially impacting UI design creativity and responsiveness.

The robust case for Chrome extensions lies in their highly customizable UI, lower processing overhead, faster development leveraging JavaScript expertise, and crucially, the significant code reusability between Chrome extension-based Gmail plugins and Outlook add-ins. This compatibility streamlines development efforts across platforms, enhancing efficiency and consistency.

When crafting a Gmail Chrome extension, essential components like InboxSDK or Gmail.js for streamlined UI development, secure OAuth flow for user data access, and robust user session management are pivotal. Consider Aurinko, a specialized backend designed for Add-ins and Workspace apps, to streamline OAuth flows and simplify integration, significantly expediting development efforts.

In essence, the selection between Chrome extensions and Google Workspace Add-ons hinges on the specific project requirements, each offering unique benefits that developers can leverage to create powerful, tailored solutions aimed at enhancing Gmail’s functionality and user experience.