API Access Key & Authentication

JSONP Callbacks

The JSONP Callbacks is a feature included in the Exchangerates API. With this feature, you can specify the function name and send it into the API’s callback GET parameter and make the API respond to your request with the API response wrapped in that function.

Example Call:

From the above example, we can see a request from the API to use the callback function MY_FUNCTION.

Example Response: Your API response will be wrapped inside your preferred callback function.

Access-Control / CORS

Cross-Origin Resource Sharing (CORS) and Access-Control Headers are also supported into the Exchangerates API. This gives you the possibility to use the Exchangerates API via Cross-Origin HTTP Requests. Learn more about CORS »

HTTP ETags

You can request new Exchangerates API data only in cases if there are changes into the rates data since your last API response, this can be done with HTTP ETags.

What are ETags?

An ETag is a part of the HTTP protocol and one of the several mechanisms used for cache validation. The ETag is an identifier assigned to a data resource in a server, and if that resource is ever updated at the server, the ETag is changed.

Whenever a resource is requested (via its URL), the data and ETag are retrieved and stored in the Web cache, and the ETag is sent along with subsequent requests. If the ETag at the server has not changed, a "Not Modified" message is returned, and the cached data is used. (Definition by pcmag.com)

ETags - Quickstart Guide

Step 1

The primary request sent to Exchangerates API will create an ETag object that will contain a unique ETag key and a Date object containing the exact date and time at which the data was last modified. This data, along with the entire API response, must be cached in order for ETags to work.

Step 2

When you will make another API request, be sure to include the If-None-Match HTTP header abd set ut to your previously generated ETag value. Moreover, you will need to add the If-Modified-Since HTTP header to your API request containing the date and time data from your last request.

Step 3

Based on if your result set has updated or not, since your last API request, the API will return:

• same results as your initial API request along with a 304 – Not Modified HTTP header which indicates that no change has happened. In this case, the size of the API response will be very small 0.2kb;

• or new results containing a completely new set of ETag and Date objects that will indicate that new data has been accessed. In this case, the size of your API response will be normal.

Potential Errors

When we send API requests but the requested data is not available or the API call fails for some reason, a JSON error is returned. Errors always come together with an error code and a description.

Example Error: The following error is returned if your monthly API request volume has been exceeded.

Other Errors: