My Postcode Shipping Extension has just been published on the Shopify marketplace.
https://apps.shopify.com/postcode-shipping-extension
Finally with this app you can setup and manage shipping rates for all countries and postcode ranges. The app supports both numeric and alphanumeric postcode ranges.
You can also calculate shipping by order weight, quantity or flat rates depending on your requirements. All of this is wrapped up in rate tiers to control which rate is provided to your customer at checkout.
The app is hosted on a first class cloud platform to ensure maximum uptime and a super quick response time.
Please note: that your store will require Real-time carrier shipping to be enabled on your store. If you currently don't have this available you can request Shopify Support to install it for you.
Regards,
Zann