Yes, ShipInsure will work with all Shopify themes.
In fact, for most themes, the widget will automatically detect the right spot to place itself so installation doesn't even require you to touch your templates at all!
For some themes, (or if there have been customizations to your theme), installation might require you to edit your template and place a small code snippet to tell the ShipInsure widget exactly where you want it to show up. If you've installed the ShipInsure app, but the widget is not showing up, you can follow the instructions for how to place the code snippet in your theme.
The ShipInsure app is running flawlessly in Shopify and Shopify Plus stores using Shopify themes like a, b, c, to paid themes like, a, b, and customized themes. We continue to test on all the major themes as new features and approaches come out from Shopify and other theme developers. The ShipInsure app has also been tested in conjunction with other cart apps related to product recommendations, free shipping, "frequently bought" products, to ensure everything "plays nice" together. We have taken great effort to write our app so that it won't interfere with other plugins or themes.
We can also Install the widget for you, with one of our seasoned Shopify developers.