Develop A Shopify App to calculate shipping using available APIs

Need a developer to create a Shopify App so we can use two services in Australia. Australia Post shipping calculation & FastWay courier shipping calculation, with the possibility of adding others later. The chosen contractor will be offered more work on the app for a later date. Final result is to be: 1. Proven to function as a working postage calculator to give buyers real time calculation when using check out and paying for item in my store. 2. Have a way of choosing which service items for sale use for their postage method FastWay or Australia Post (This can be decided by items weight and if it is oversized or not) 3. Delivered to and be owned soley by me on completion. 4. Able to support some items which are oversized and will have to be sent by FastWay couriers rather than Australia Post. For example: items under 15kgs can be sent by Australia Post & items over 15kgs and items which are oversized are all sent by courier (FastWay). Both Aus Post have API's available, we need to be able to use weights from product descriptions & manually input product dimensions using the APIs to calculate accurate shipping upon checkout. These are two apps best to compare to, they both have free demos available: [login to view URL] [login to view URL] I have demo accounts and API access for both FastWay & AustraliaPost ready. If you have any better suggestions from the project we are flexible and just want to see a working calculator app on check out!! Thank you, we look forward to hearing from you!