foursquare2 is a Ruby wrapper for version 2 of the Foursquare API. Users will need to implement the OAuth2.0 gem as well, since the foursquare2 gem doesn't handle the API's OAuth 2.0 authentication flow.
The 600 million numbers that Truecaller has in its directory have been collected via crowd-sourcing. Truecaller’s users can share their contacts and in return they get access to search in the collaborative database. Thanks to this collaborative data solution, the directory is growing and being updated continuously. It also contains numbers that no other directories have, e.g. pre-paid phones.
Twitter today announced that it is launching a new offering that will give developers access to the full Twitter archive which contains all tweets going back to the first one posted by Twitter CEO Jack Dorsey in 2006. Previously, full archive access was limited to Twitter's enterprise customers.