Where is documentation for REST API?
How do I get all of my data through REST API?
By default our API returns 25 records but it can be overwritten using per_page query parameter to get 50 records matching the criteria. If there are more than 50 records then you can paginate from page 1 to page 30 so this allows you to get max of 1500 records for a query.
If you have more than 1500 records then you would need to narrow your criterial and iterate through those. Here is a bash script using curl to give you an idea. You would need to implement similar logic in programming language of your choice.