Why do you return only 700 keywords for domain / for keywords?
DataForSEO Google Ads API returns up to 700 keyword suggestions due to Google AdWords API restrictions. Unfortunately, Google does not return more than 700 keyword ideas for a domain or specified search term(s). We never know how many keyword suggestions Google AdWords API will provide you with, and we cannot affect the returned number anyhow. The only known limit is 700 keywords which is the maximum possible number of returned search queries through Google AdWords API.
If you would like to obtain more than 700 keyword suggestions, you can try using DataForSEO Labs API instead of Keywords Data API.
DataForSEO Labs API returns up to 1000 keywords in response to one task. It offers three powerful keyword research algorithms and provides data based on our in-house Keyword Database of over 4 billion keywords.
Learn more about using DataForSEO Labs API for keyword research in our article.