# Manifest APIs When updating existing app, you can use these manifest APIs as an alternative to using the build UI. - [Export](/docs/api/marketplace/#tag/manifest/get/marketplace/apps/{appId}/manifest/) an app manifest from an existing app. - [Validate](/docs/api/marketplace/#tag/manifest/post/marketplace/apps/manifest/validate/) an app manifest before using it to update an app. - [Update](/docs/api/marketplace/#tag/manifest/put/marketplace/apps/{appId}/manifest/) an app with a manifest.