Are there free (open source) analogues of dadata.ru?

Question

big data

Are there free (open source) analogues of dadata.ru ?
Interested in "unique" elimination of duplicate addresses and contact details of customers. There are open databases of addresses, most likely databases of names too. Are there open source algorithms for finding matches on similar data in different formats.

1. Addresses
   
2. Contact information about the person
   

Answer 1

For addresses, I'm looking at a shareware service:
https://kladr-api.ru/