---
title: "[Extensions] - About Sidebar Extensions"
description: Overview of Custom Sidebar Extensions, including examples, prebuilt options, and resources to create or use them.
url: https://www.contentstack.com/docs/developers/create-sidebar-extensions/about-sidebar-extensions
product: Contentstack
doc_type: concept
audience:
  - developers
version: current
last_updated: 2026-03-25
---

# [Extensions] - About Sidebar Extensions

This page explains what Custom Sidebar Extensions are in Contentstack, what they’re used for, and where to find resources to create new extensions or use prebuilt ones. It’s intended for developers who want to extend entry editing capabilities within a stack using sidebar-based widgets.

## About Sidebar Extensions

**Note**: Experience Extensions use the legacy approach with extensions. We recommend using the  [Sidebar UI Location](/docs/developers/developer-hub/sidebar-location/) for the Contentstack App Framework to extend the functionality of your apps.

**Custom Sidebar Extensions **are powerful functionalities that you can integrate into your [stack](/docs/developers/set-up-stack/about-stack) to analyze your [entry](/docs/content-managers/working-with-entries/about-entries) content and recommend ideas. These Custom extensions allow users to provide additional capabilities over content, thus optimizing the content to suit their requirements.

Examples of such custom widgets are SEO tag recommendations, sentiment analysis, language translation, and so on.

While Contentstack provides certain prebuilt Sidebar Extensions ([Text Intelligence](/docs/developers/create-sidebar-extensions/monkeylearn), [Gatsby Preview](/docs/developers/create-sidebar-extensions/gatsby-preview)), you can code your own custom extensions and use it in your [content types](/docs/developers/create-content-types/about-content-types).

**Note:** Custom Sidebar Extensions are stack-specific, i.e., it cannot be used in or shared across multiple stacks.

Here are some resources to get you started with Custom Widgets:
- [Create new custom sidebar extensions](/docs/developers/create-sidebar-extensions/create-a-new-sidebar-extension/)
- [Use prebuilt custom sidebar extensions](/docs/developers/create-sidebar-extensions/use-prebuilt-sidebar-extensions/)

You can create new custom sidebar extensions by writing your custom code, or you can use the prebuilt templates by modifying the given code to suit your requirements. Both the methods are explained in detail in the above pages.

Additionally, you can browse through the topics mentioned in our “More Articles” section to learn more about Custom Sidebar Extensions.

## Common questions

### Are Sidebar Extensions the recommended approach for new development?
**Note**: Experience Extensions use the legacy approach with extensions. We recommend using the  [Sidebar UI Location](/docs/developers/developer-hub/sidebar-location/) for the Contentstack App Framework to extend the functionality of your apps.

### Can Custom Sidebar Extensions be shared across multiple stacks?
**Note:** Custom Sidebar Extensions are stack-specific, i.e., it cannot be used in or shared across multiple stacks.

### Where can I start if I want to build a Custom Sidebar Extension?
Here are some resources to get you started with Custom Widgets:
- [Create new custom sidebar extensions](/docs/developers/create-sidebar-extensions/create-a-new-sidebar-extension/)
- [Use prebuilt custom sidebar extensions](/docs/developers/create-sidebar-extensions/use-prebuilt-sidebar-extensions/)

### What are examples of Custom Sidebar Extensions?
Examples of such custom widgets are SEO tag recommendations, sentiment analysis, language translation, and so on.