There is no API to get all user profile in a single request. You need some filter and paging to get user profiles.
Using Search API
{site url}/_api/search/query?querytext='FirstName=A*'&startrow=0&rowlimit=100&sourceid='B09A7990-05EA-4AF9-81EF-EDFAB16C4E31'
In first request, above API will return you 100 profiles who have first name started with A
. In second request startrow
will be 100
. This way you can get your all user profiles.
Using UserInformationList
You can get all user profiles under your current logged in site from below end-point. Make a GET request to the following URL.
/_vti_bin/ListData.svc/UserInformationList?$skip=0&$top=100
In next requests increment the value of $skip
(previous + 100)
.