Though we're not free, you can accomplish this using Intuitive Shipping and also create shipping rules for customers outside of these zones (assuming you ship outsize of the postcode zones). The problem with free apps is that nothing in life is free, so the developers are making money off of you in some way, likely through selling data. To support ongoing development, server infrastructure and payroll (employees like to be paid!), good quality apps will have a monthly fee.
Not a free app, but, you can use the Multi Carrier Shipping Label app that helps you calculate and add shipping rates based on different factors like Zip codes, Country, States, etc. You can create a shipping zone to add the required zip codes and then configure the shipping rates for the particular zones. You can look into this guide to get a better idea regarding the same.
Hello Ally ,
Yes , basically shopify helps create shipping labels and rates depending on regions or provinces such as Laval , Quebec, Vancouver... I am looking to create subregions for these provinces taking into consideration that I am only able to deliver inside one province to limited Zip codes.
Thank you for reaching out.