There are a lot of apps that helps with international selling. Choosing the right one depends on your exact requirements. As a first step, you can look into this Shopify International shipping guide to get a better understanding regarding the selling process. Regarding the apps; may I know which carriers you are planning to use? For all top carriers, you can check out our Multi Carrier Shipping Label app that helps you integrate most carriers and seamlessly handle the international selling process.
You can also look into some of the other apps that helps with international selling here. Now, if you are looking for apps that provide you with their own discounted shipping rates, you can check out some of the apps here.
Julie here from Shopify Support.
As @PluginHive mentioned, there are plenty of apps available to help you with international selling. However, apps should be installed with a specific purpose in mind. What kind of app are you wanting to use for international selling purposes? For example, are you wanting to offer multiple currencies and languages? Are you looking for a multi-carrier shipping solution, as @PluginHive suggested?
If you're looking to translate your store into multiple languages, then you can consider a translation app. There are also currency apps that will allow you to display your product prices in your customers' local currency. Both types of apps will add a language or currency selector to your website, giving customers the ability to choose their preferred language and currency. Some of these apps will also automatically display your website content in their local language and currency, based on the location of their IP address.
We have plenty of resources to help you expand your business internationally, including a collection of help docs on how to sell cross-border. There are also a couple of blog posts in the Shopify Blogs that you should find useful, like "The Ultimate Guide to Selling Globally on Shopify" and "How to Expand Your Shopify Store to Multiple Countries".
In these guides, you'll find tips on how to offer the right local payment and shipping options for international customers. You'll also learn how to identify your target international markets and how you can effectively market towards them.
I hope this leads you in the right direction and provides you with some apps worth considering. I'd also love to hear what you think about these blog posts and your plans for selling internationally.
Looking forward to your response!