> For the complete documentation index, see [llms.txt](https://developer.harness.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.harness.io/feature-management-experimentation/management-and-administration/integrations/vercel.md).

# Vercel

{% hint style="danger" %}
**NOT SUPPORTED IN PROD 3**

The Harness FME integration for Vercel is not supported in Prod 3.

If you are using Prod 3 in Harness, contact [Harness Support](/feature-management-experimentation/troubleshooting-and-resources/fme-support.md) or [submit a feature request](https://ideas.harness.io/feature-request).
{% endhint %}

[Vercel](https://vercel.com/) is an advanced hosting and deployment platform for modern web applications. Developers can incorporate serverless code that runs in the Edge Runtime on the Vercel platform using [Edge Functions](https://vercel.com/docs/concepts/functions/edge-functions) and [Middleware](https://vercel.com/docs/concepts/functions/edge-middleware).

Vercel supports compute logic in Edge Functions and Middleware that is scalable, on-demand, and stateless with the [Edge Config](https://vercel.com/docs/storage/edge-config) low-latency data store. Harness FME provides an out-of-the-box integration that wraps the Edge Config data store, allowing near-instant reads at the edge.

To configure the Harness FME integration for Vercel:

* Add the Harness FME integration to your Vercel project
* Set up the FME JavaScript Browser SDK client

The integration setup process requires Harness admin-level access. You can create a Harness account during the Harness FME integration setup.

### Architecture of the integration <a href="#architecture-of-the-integration" id="architecture-of-the-integration"></a>

The following diagram shows the architecture of the Split (renamed to Harness FME) integration for Vercel.

![Vercel Harness FME integration architecture diagram](/files/jkD9V0r9OfVDS9UVAq7b)

The Harness FME integration for Vercel writes the FME definitions (the set of feature flags and segment definitions) to the Edge Config instance of your application, and keeps this data synchronized. The Edge Config wrapper is an adapter that connects the FME SDK with the Edge Config, allowing the SDK to rapidly evaluate feature flags. The SDK sends tracked events and impressions data to Harness servers.

### Add the Harness FME integration to your Vercel project <a href="#add-the-harness-fme-integration-to-your-vercel-project" id="add-the-harness-fme-integration-to-your-vercel-project"></a>

To add the Harness FME integration in Vercel:

1. Add an instance of the Edge Config to your Vercel project. The integration will add a root-tree to the JSON contents of your Edge Config instance, but will never erase or overwrite any other existing JSON data.
   * If you forgot to add the Edge Config instance, you can restart by adding the Harness FME integration to your Vercel project from this step.
2. Navigate to the [Split integration](https://vercel.com/integrations/split) or search for **Split** in the Vercel Marketplace, click **Connect Account**, and follow the setup process.
   * You will be prompted to log in or create your Harness account, and then you will see the Vercel setup page.
   * Specify each [Harness FME environment](/feature-management-experimentation/management-and-administration/environments.md) and choose the Edge Config instance that each should sync to. You are given an authentication key for each environment to use in your code to access the correct JSON root-tree for that environment in your Edge Config instance.
   * Click **Save** to save the setup for all environments. Then, click **Finish integration**.

### Set up the Harness FME JavaScript Browser SDK client <a href="#set-up-the-harness-fme-javascript-browser-sdk-client" id="set-up-the-harness-fme-javascript-browser-sdk-client"></a>

To set up the FME SDK in the code of your Vercel project:

1. Install the required packages by running the `npm install` command.

   ```bash
   npm install @splitsoftware/splitio-browserjs @splitsoftware/vercel-integration-utils @vercel/edge-config
   ```
2. Instantiate the SDK within your Vercel Edge Function or Middleware. The FME SDK client must run in *partial consumer* mode and be initialized with the Edge Config wrapper. For more information, see the [Vercel integration using Edge Config and Split SDK GitHub repository](https://github.com/splitio/vercel-integration-utils/tree/main/example/pages/api/get-treatment.js). The `core.initializationKey` passed to the `SplitFactory` constructor is your client-side API key for your Harness FME environment.

Once your setup is complete, you can consume FME feature flags from Edge Config and send events to Harness servers.

#### Manage the integration after installation <a href="#manage-the-integration-after-installation" id="manage-the-integration-after-installation"></a>

For more information about managing the integration, see the [official Vercel documentation](https://vercel.com/docs/integrations/using-an-integration/manage-integration).