I’ve read in several places that Twitter does NOT support searching users by email via the public API. Are there private options available for startups or other businesses?
No, there is no API option to find Twitter users by email address.
Not at all? So, I have to use a 3rd-party service?
I don’t know of third party services that offer this either.
Twitter only recently enabled app developers to request access to a user’s email address.
Digits by Twitter does provide a phone-number/address book-based lookup but there is no connection between Digits accounts and Twitter accounts.
Services like Clearbit seem to offer this capability…is there a reason Twitter doesn’t offer this? I believe it is the only social media platform that does not do so
I can’t comment on this much other than the history and capabilities of the API, which has never offered this functionality. Twitter has always taken a strong approach to user data privacy, which is one reason why up until about 2 years ago the API didn’t offer the option to even get an email address from an OAuth login, and developers were required to gather that information separately (this has now changed).
Incidentally, I’ve never used Clearbit but just checked my details, which were inaccurate! I suppose they are pulling the information from different public profile sources, and in my case that’s outdated, so YMMV.