What replace now the http://search.twitter.com/search.atom?q= is it https://api.twitter.com/search.json?q=
But for search.atom did need user to login and json need it .
Is there is a way to make serach for hashtag without login?
There’s no way to use the search API in 1.1 without using authentication – you don’t necessarily need to use a “login” but you do need to at least use app-only auth.
API v1.1’s search endpoint is at https://api.twitter.com/1.1/search/tweets.json – there’s documentation for it on this site.