PT Tokopedia, Indonesia's largest online marketplace, has become the country's most valuable startup after raising $US1 billion ($1.4 billion) from existing investors including SoftBank, according to people familiar with the matter.

Perseverance paid off for William Tanuwijaya. Credit:Bloomberg

The e-commerce operator is valued at about $US7 billion ($9.7 billion) after the round, the people said, asking not to be identified as the details are private. That would top the valuations for startups in Indonesia, according to the research firm CB Insights. While it wasn't clear if the backing comes from SoftBank Group Corp. or its Vision Fund, the Tokyo-based company transferred prior holdings in Tokopedia to the fund earlier this year.

William Tanuwijaya, the 37-year-old son of a factory worker, co-founded the company and has capitalised on the country's rapid adoption of smartphones and increasing comfort in shopping online. Indonesia's internet economy is the largest and fastest growing in Southeast Asia with e-commerce poised to be worth $US53 billion by 2025, according to a recent report by Google and Temasek Holdings Pte.

A cashed-up Tokopedia, which was founded in 2009, will present more formidable competition for its rivals. China's Alibaba Group Holding Ltd. is expanding its Lazada business in Southeast Asia, while PT Bukalapak.com is signing up hundreds of thousands of neighborhood stores as partners and Singapore's Sea Ltd. is investing heavily to expand its e-commerce business.