This article was first published on Dec 17, 2014, and updated on May 12, 2015.

SINGAPORE - Parliament on Monday approved a Bill making it necessary for third-party taxi booking services to register with the Land Transport Authority of Singapore (LTA) in order to operate here.

Under the proposed new law, service providers with more than 20 participating taxis must adhere to a set of guidelines such as specifying fares upfront and providing LTA with live data on bookings.

With a plethora of taxi applications competing for attention, here is a rundown of the apps that are available to taxi commuters.

Taxi-Taxi@SG

WHAT: Launched in December 2014 by the LTA.

HOW IT WORKS: The app, unlike its rivals, does not book cabs for users but is meant to make it easier to hail a taxi on the street. It allows commuters to see the locations of all available taxis from the fleet of 28,000 in Singapore, unlike other third-party apps which only show those cabs which have signed up with them.

Using this information, users can then decide whether to keep waiting or walk to another area with more taxis.

The app also allows commuters to broadcast their locations, allowing cabbies to see areas of high demand.

GrabTaxi

WHAT: Launched in October 2013, GrabTaxi was one of the first independent taxi booking apps to take off in Singapore. The app was first established in Malaysia as MyTeksi, and is founded by Harvard Business School graduates Anthony Tan and Tan Hooi Ling.

HOW IT WORKS: The location-based app shows users the number of available taxis from all cab companies in the area. Users key in a destination, select their cab type, and book a ride. Cabbies will have to bid for the job. Those who bid within 30 seconds and are closest to the passenger's location will get it. The passenger will receive the driver's licence plate number, estimated time of arrival, and the estimated taxi fare. Passengers can make calls to the cabby or see the taxi's current location, as well as rate the cabbies after the ride.

The app regularly holds promotions to give passengers discounts on their rides. It started accepting credit card payments this year and is intending to roll out a cashless payment system in the coming months. The same app now works across six countries - Singapore, Malaysia, Philippines, Thailand, Vietnam and Indonesia.

A licensed private vehicle booking service, called GrabCar, is also available via the app.

Easy Taxi

WHAT: Founded in Brazil, the app launched in Singapore in December 2013. The app operates in more than 80 places including Ecuador, Taiwan and Hong Kong.

HOW IT WORKS: Like GrabTaxi, Easy Taxi uses GPS to detect locations of the passengers and cabbies. When a passenger makes a booking via the app, drivers within a certain radius will receive an alert. The radius widens if no one picks up the booking after a while. But unlike GrabTaxi, which blasts a request for 30 seconds, Easy Taxi tries for three minutes before it deems the booking as unsuccessful.

The app also provides passengers with a taxi driver's contact details, licence plate number, car model, estimate time of arrival and real-time location. The cabbies can also call their passengers.

The app recently partnered messaging app WeChat to allow WeChat users in Singapore to book a cab via the messaging app.

MoobiTaxi

WHAT: Set up by homegrown company Maven Lab, MoobiTaxi hit the app stores here in July 2013.

HOW IT WORKS: The app works as a booking aggregator, and is linked to the servers of taxi operators. This means that when a passenger makes a booking via the MoobiTaxi app, the alert is flashed out to cab drivers through the operators' official booking channels.

The app has a booking feature, which works similarly to GrabTaxi and Easy Taxi, and a check-in feature, which allows passengers to "e-hail" a cab.

The check-in feature is has no booking fees and allows passengers to broadcast their pickup locations to cabbies around the area. The catch - it does not guarantee one a cab, and can be fruitless sometimes.

UberTAXI

WHAT: The United States-based company has offered private car-sharing services here since 2013. But in September that same year, it launched a taxi booking app similar to Easy Taxi and GrabTaxi.

HOW IT WORKS: The taxi booking app is similar to that of Easy Taxi and GrabTaxi, but a customer's credit card information is stored into the system at the point of signing up. At the end of a trip, passengers simply alight the taxi, with the fare being automatically deducted from the credit card.

The company's has other services such as UberX and UberExec, which provides private cars for hire. For these services, the company sets its own fees. For instance, a booking made under the UberX service, which includes cars such as Hyundai Sonata and Nissan Sunny, fares start from $3.50 in off peak hours and increases every 30 cents per minute or 50 cents for each kilometre. It has a minimum fee of $8, and those who cancel their rides will have to pay a penalty of $6.

Hailo

WHAT: The London-based app entered Singapore in October last year with a partnership with SMRT Road Holdings, making it the first third-party app here to partner a local transport operator.

HOW IT WORKS: Passengers can get a cab with just two taps using this app. On launching Hailo, users can see where Hailo-connected cabs are and 'hail' them with a tap, at which point drivers can choose to "Accept Hail," get the passenger's location, and pick them up.