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One of the most unsung features of iOS 8 is right underneath your finger.

Apple’s new mobile operating system lets third-party apps access the Touch ID (fingerprint) feature in the iPhone 5s, iPhone 6, and iPhone 6 Plus. So now, with the free iOS app 1Password and a bit of preparation, you can log in to an online account with just a quick scan of your fingerprint.

At least in theory. Though 1Password represents the holy grail for many people — the ability to both keep your passwords secure in an encrypted vault and bypass annoying log-ins by simply holding a finger on the home button — it’s not nearly as seamless as anyone would like it to be.

That’s because the 1Password app is currently compatible with very few mainstream apps. So few, in fact, that I can list them here: Etsy, TweetBot, and VSCO Cam (those, and a few indie ones).

We hope that, as 1Password attracts more fans, the developers of popular apps will make their products work with it. In the meantime, you can use 1Password to speed through logins on websites when you’re using your Safari browser. (1Password is also available as an app and a browser plugin for Mac, Windows, and Android.)

Before you take the dive, it’s important to understand the security implications of 1Password. The service doesn’t actually make sites like Amazon and Facebook lockable by fingerprint. Rather, 1Password uses your fingerprint to unlock its own vault, which holds your passwords to those other services. That means that you must use a super-secure password to secure your vault, and that you must continue to use complex and unique passwords for each individual service. Otherwise, your accounts remain susceptible to being hacked the old-fashioned way.

And keep in mind that the trade-off to security is convenience. Even with 1Password, each login takes about five taps on your phone. That’s probably less effort than manually typing in a password, but it’s still a drag. Albeit a very necessary drag.

Here’s how to use 1Password on your iPhone:

1. Download the iOS 8 app here.

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2. When you open the app, it’ll ask you whether you’d like to sync with an existing 1Password account or start a new one. If you’re new to this app, select the latter. Tap Create new vault.

View photos 1Password welcome screen More

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