# Addons overview

> What addons are, the 5 types you can build on the Classic and Modern engines, and how to find, install, and use one from the Community Marketplace.

An addon extends Testsigma's built-in actions with your own. Testsigma covers most user actions in plain English, but an application often needs something the built-in set does not have.

Take an application that keeps loading entries as you scroll, such as a product listing. A test that has to reach the copyright notice at the bottom cannot get there with a fixed number of scroll steps, and an addon can scroll until the page stops growing.

Addons are engine-specific. Classic applications use Java addons and Modern applications use TypeScript addons, and an addon built for one engine does not appear in an application running on the other. An application's engine is fixed at creation.

## What you can build

Both engines support the same 5 addon types.

| Type | What it gives a test author |
|---|---|
| Custom action | A step in the test step editor, with a grammar you define |
| Test data generator | A data generator in test data fields, alongside the built-in ones |
| Conditional If | A condition of your own logic, running its child steps when the condition matches |
| While loop | A condition of your own logic, repeating its child steps until the condition matches |
| Post-plan hook | A callback that runs after a test plan finishes, whatever the outcome |

On the Modern engine those 5 collapse into 4 SDK helpers, because a Conditional If and a While loop are the same helper with a different `stepActionType`:

| Capability | SDK helper |
|---|---|
| Action | `defineAddonTemplate()` |
| Condition | `defineAddonTemplate()` with `stepActionType` set to `IF_CONDITION` or `WHILE_LOOP` |
| Test data function | `defineTestDataFunction()` |
| Hook | `defineHook()` |

A condition is hidden from the ordinary action list, so it appears only where a condition is expected.

Only AFTER hooks run today. `hookType: "BEFORE"` exists in the SDK types but is reserved for a future release.

## How an addon reaches a test author

An action appears in the step editor for the platforms declared in its `applicationType`. The test author fills its placeholders with test data and elements, then names a runtime variable for each output.

A test data function appears wherever generated data is accepted: step test data, for-loop bounds, and step group parameter overrides. A hook is configured on a test plan and runs automatically.

A Unified workspace sees addons declared for **ANDROID**, **IOS**, or both. A web-only addon is not offered there.

A test data function has no access to the page under test and cannot write runtime variables. That restriction is what lets the platform call it anywhere a value is needed.

## The Community Marketplace

The marketplace is where addons are discovered and published. Click the addons icon in the navigation bar to open it.

- **Community**: addons published by the community and available to everyone, sorted into **Featured** for the top-rated, **New and Updated Addons**, and **Testsigma Addons** for the official ones
- **Installed Addons**: what is installed and active in your account
- **My Addons**: what you have created, public and private

A private repository is available too, for an addon holding proprietary code you do not want to share. Where nothing in the marketplace suits, build your own and publish it there.

### Find an addon

Search from the bar below the **New Addon** button. The list sorts by **Package Name**, **Creation Date**, or **Last Updated Date**, and filters by **Tag**, **Application Type**, **Ratings**, **Creation Date**, and **Last Updated Date**.

An addon's details page carries its name, creator, creation date, description, rating, install count, supported application types, supported actions, the data generators it provides, and a **Download Source Code** button.

### Install and use an addon

1. Click the **Addons** icon in the left navigation bar.
2. Find the addon in the **Community** tab, by browsing or searching.
3. Click **Install**.
4. Refresh the page.

Refreshing is required. Without it the addon's actions do not appear in your test cases.

To use it, start typing the action name in a test step and select it from the suggestions. The **Installed Addon** tab shows each installed addon's available actions.

![An addon's details in the Community Marketplace, listing the actions it adds](https://s3.amazonaws.com/website-static-docs.testsigma.com/new_images/projects/Updated_Doc_Images/update_addon_marketplace_3.png)

## Before you build your own

| Classic (Java) | Modern (TypeScript) |
|---|---|
| Core Java, OpenJDK 11 | Node.js 22 or later |
| An IDE such as IntelliJ or Eclipse | pnpm or npm |
| Maven or Gradle | An IDE |
| Selenium basics | Basic TypeScript |
| Lombok annotations | Modern addon features enabled for your account |

See [Build your own addon](https://testsigma.com/docs/v2/addons/build/) for the workflow on both engines, and [Addon SDK reference](https://testsigma.com/docs/v2/addons/sdk/) for what a Modern addon's execution context exposes.