Zapp! Flutter projects can access instant previews via the domain. This is a great way to share your work with others, or to test your project on different devices.

Preview Example

Previewing your project#

To preview your project, add your project ID as the subdomain to

For example if your project URL is, vist to preview your project.

Note; only the random ID is required - if the project URL changes when updating project information, the preview URL will continue to work for older URLs you might have shared (e.g. is the only part of the URL that is actually required).

Preview metadata#

The underlying HTML of your preview is pulled directly from the web/index.html file in your project (one is automatically created if you don't have one already). This means you can add any metadata you want to your preview, such as a title, description etc. Visit the file explorer documentation to learn more about the web directory.

Using as a host#

Although your projects are exposed to the world via a uniquely hosted URL, we do not recommend using this service as a host for your Flutter application. We do not provide any guarantees about uptime, and we may change the underlying hosting infrastructure at any time.

Instead, you should opt to using a hosting provider with an underlying CDN, which is able to host your Flutter application behind a cache. Some options include: