App should have the basic capability of letting customers receive reminders and they should be able to write reviews from their emails. I liked kudobuzz, but its integration is very limited.
If you have international customers who speak other languages, response is lower when you speak to them in English. Solutions like Trustpilot handle that. Have implemented them plus some other methods for international customers in various countries, would be good to know a bit more about your specific requirements and share some tips on a phone call.