Twitter has launched a new sign-in service called Digits. It's for developers who want to add a password-free login option to their apps.

The company announced Digits at Flight, its first annual developer conference. Although Digits is just one of many Twitter-made tools being launched today, it is unique in that it allows you to sign up and log into apps using just your phone number rather than a password and username.

Digits uses SMS to control who accesses your accounts and safeguards accounts using Twitter's infrastructure. More specifically, apps will verify an entered phone number via a SMS-based confirmation code. The idea sounds similar to two-step verification, though it also works for web applications.

Digits is Twitter's way of embracing app developers as well as embedding itself into potentially hundreds of new apps. Twitter has a long history of shunning developers but has to take a different approach now that it is a public company in need of expanding.

Digits is launching today in about 200 countries and for 28 languages. Developers only have to add few lines of code into their apps in order to include Digits' login service, meaning you should start seeing the new sign-in method in some of your favourite apps soon.

At launch, the Digits website lists Fitstar, Resy, and OneFootball as a few apps now on board. Presumably, Twitter is on that list too.

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