laravel-exchange-rates | Laravel wrapper package | REST library

To clear your confusion on the conflicting statements you're referencing:

Caching just means to store the data. Examples of where the data can be stored are in memory, in some persistence layer (like Redis), or in the browser's local storage (like you mentioned). The intent behind caching can be to serve the data faster (compared to getting it from the primary data source) for future requests/fetches, and/or to save on costs for getting the same data repeatedly, among others.

For your case, the http://exchangeratesapi.io/ API is advising consumers to cache the results on their side (as you mentioned in your question, this can be in the browser's local storage, if you're calling the API front front-end code, or stored in memory or other caching mechanisms/structures on the server-side application code calling the API) to that they can avoid the need to introduce rate limiting.

The project from Github you're referencing, Laravel Exchange Rates, appears to be a PHP wrapper around the original API - so it's like a middleman between the API and a developer's PHP code. The intent is to make it easier to use the API from within PHP code, and avoid having to make raw HTTP requests to the API and avoid processing the responses; the Laravel Exchange Rates handles that for the developer.

In regards to the

By default, the responses all of the requests to the exchangeratesapi.io API are cached

statement you're asking about, it seems the library follows the advice of the API, and caches the results from the source API.

So, to sum up:

1. http://exchangeratesapi.io/ is the source API, and it advises consumers to cache results. If your code is going to be calling this API, you can cache the results in your own code.
2. The Laravel Exchange Rates PHP library is a wrapper around that source API, and does cache the results from the source API for the user. If you're using this library, you don't need to further cache.