Call Structure

To return the options that are displayed at, or prior, to checkout, you need to call the find service from your Order Management System or equivalent service. You do this by making an HTTPS GET request to the service, incorporating a string of query parameters, including the API key with which you have now been provided (refer to Configuring your Security).


For test purposes, it is advisable to install a package that will allow you to store and run a collection of calls, such as Postman or Insomnia.

The parameters are concatenated using the & character, for example:



The key can be inserted anywhere in the string, but it must always be present.

There is a minimum set of requisite parameters, and these are listed in Basic Parameters. You can add further parameters as required, and these are listed in Extended Parameters.


The more parameters you add, the more specific to the consumer the options returned are likely to be.

If you receive an HTTP 200 OK response, then your parameters, including the API key, are being successfully validated and you can carry on with making more customised calls. Otherwise, please contact Metapack support.


For the full list of possible server responses, refer to What are the possible Server Responses?.