# Watchlist API prerequisites

Before you can use the Watchlist API, you may need to upgrade and configure one or more of the components detailed on this page.

## Client-side requirements

You need to be running at least version 4.0.3 of Caplin Trader. Please upgrade Caplin Trader if required.

## Server-side requirements

You need to be running at least version 6.2.3 of Transformer and at least version 6.2.2 of the Watchlist Service blade, and follow the instructions to [enable support for Transformer hosted watchlists](../../../caplin-platform/transformer/configure-transformer-to-host-synchronised-watchlists.md).

For instructions on Deploying the Watchlist Service blade, see [Deploying the WatchList Service](../../../caplin-platform/transformer/configure-transformer-to-host-synchronised-watchlists.md).