Twitter’s Digits helping developers build social graphs for apps by requesting users’ contacts

Twitter’s Digits, the social network’s login product, will now let developers request access to the contacts on users’ phones through what it’s calling a “friend-finding” tool.

Digits, which Twitter launched in October, allows users to sign up for and log in to apps or Web-based services using their phone numbers.

Now, in an update geared to extending social graphs to apps, Digits is letting developers ask users for their current contacts, Twitter said this morning. The company made it clear that process is a request, and doesn’t require users to agree to share those contacts.

“While social networking services give you the full list of your users’ friends, those connections may not be up to date or relevant to the app experience you’re delivering,” Twitter wrote in a blog post. “On the other hand, contact lists on your users’ phones have the strongest, most current connections — but it can be cumbersome to build custom code to import those lists and match the contacts to create a social graph.”

According to Twitter, friend-finding gives developers the ability to build social graphs around their apps. “Digits will match both mutual or one-way connections so users who are already on the service will know immediately which of their contacts are also using your app,” Twitter said, “and they can also be alerted when a friend joins later.”

Twitter thinks that friend-finding will improve users’ experience in other ways, as well, such as personalizing content, showing what friends purchased, or what level they’ve reached in a gamified app.

The Digits update also includes two-step verification, which lets user log in to apps with their phone number and then set up a code, which they will be prompted for on future sign-in attempts.