Credit card firm MasterCard on Tuesday (Oct 4) officially introduced a new biometric payment technology that allows its customers to make online payments with either a selfie or a fingerprint.

Now available in 12 European countries including Britain, Germany and Spain, the payment method will gradually be made available across the world in 2017.

Here are some other interesting ways to pay that forgo the hassle of remembering a password.

Voice

Officially unveiled in June this year on both iOS and Android devices, Google's Hands Free app eliminates the need for users to take out their phones or wallets to pay.

How it works: The user simply says "I'll pay with Google", the cashier confirms his identity via his photo and voila, payment is made. Purchase details will be sent to the user's phone after each transaction.

Hands Free reportedly utilises a mix of Bluetooth low energy, Wi-Fi and location to detect that the user is at a store that supports the app.

Currently, it can be used only in the San Francisco Bay Area in the United States at a limited number of eateries, including McDonald's.

Mobile phone

The introduction of Apple Pay in Singapore in April this year was followed by the launch of Google's Android Pay service two months later.

Both digital wallet services enable users to save into their phones credit and debit cards issued by five major banks here: POSB, DBS Bank, OCBC Bank, United Overseas Bank and Standard Chartered Bank.

The wireless Near Field Communication (NFC) technology is used to transmit data between the mobile phone and a contactless payment reader.

Users will still need to place their fingers on the phone's fingerprint sensor to authenticate a transaction.

Such readers are available at 30,000 retail points in Singapore, including at NTUC FairPrice and Cold Storage supermarkets, as well as Guardian, Starbucks and Uniqlo outlets.

Watch

If using your phone to make payment is still too mainstream, how about the Apple Watch?

While it also utilises Apple Pay, the watch works independently of an iPhone, which means users who have both devices can register two separate credit or debit cards and make payment with either one at their convenience.

Eyes

Japanese firm Fujitsu released its Arrows NX F-04G smartphone in May last year - the world's first to come equipped with iris recognition technology.

The phone's users can unlock websites and access information using only their eyes, which the NX F-04G scans using its front-facing camera.

Users can also store credit card information and pay for online purchases merely by staring into the screen.

The phone is currently available for sale only in Japan.

Heartbeat

Okay, it's still not available officially, but MasterCard announced in February its intention to roll out a heartbeat-authenticated payment.

It conducted its first trials in August 2015 in Canada and the Netherlands using the Nymi band, which contains a sensor that reads its wearer's electrocardiogram - the unique electrical signal produced by the heart.

While response was positive, MasterCard's president of enterprise security solutions Ajay Bhalla told The Verge website that there is currently no available infrastructure to support it.