Indonesia's Go-Jek launched a trial version of its ride-hailing taxi app in Singapore yesterday, ahead of a full entry planned early next year as it aims to take on market leader Grab.

Go-Jek is in the middle of a $500 million expansion plan beyond its Indonesian base with a focus on Southeast Asia and has recently introduced services in Vietnam and Thailand.

It operates a fleet of motorcycle taxis, private cars and other services - from massage and house cleaning to grocery shopping and food delivery - available via smartphone, although the Singapore launch will only offer car taxis.

"Today marks the journey for us to be in Singapore so we are super excited, super humbled," Go-Jek President Andre Soelistyo told reporters.

The Singapore market has been dominated by homegrown tech firm Grab since it bought U.S.-based rival Uber's ride-hailing and food business in Southeast Asia earlier this year, ending a bruising competition. In return, Uber received a 27.5 percent stake in Grab.

Singapore's anti-monopoly watchdog fined both Grab and Uber for breaking competition rules during the merger.

Soelistyo said Go-Jek's arrival would help to ensure "healthy competition."

Go-Jek's beta app was due to be available for download from yesterday to a limited number of customers, and will only cover a designated part of the city-state.

Beta versions are used to test and gain feedback from a restricted number of users before full service begins. Go-Jek has partnered with Singapore's biggest bank DBS, hoping to tap into the lender's customer base to drive market share, and offering benefits to its customers in return. Go-Jek has won financial backing from investors including Google, Singapore's sovereign wealth fund Temasek and Chinese internet giant Tencent. Southeast Asia's ride-hailing market is expected to reach $20 billion by 2025, according to research by Google and Temasek.