When a venture launched by four people from Delhi is picked by Y Combinator, it can’t help getting noticed. That’s because the California-based incubator is the holy grail for startups, having given birth to unicorns such as Uber (the world’s highest-valued startup), social media network Reddit, hotel aggregator Airbnb, and cloud storage service DropBox.

ClearTax, the Delhi company Y Combinator picked, is in the online tax filing and consulting business. Co-founder and CEO Archit Gupta was inspired by his chartered accountant father Raja Ram Gupta to find a technological solution for tax payers. The market for this service is highly fragmented and dominated by traditional chartered accountants, some of them running family-legacy firms.

Gupta and his co-founders Ankit Solanki and Srivatsan Chari, friends from their IIT Guwahati days, regrouped after working for a few years to create a simple interface that would let people navigate the government’s e-filing process. Gupta says he has been investing in making the e-filing products more functional and easier to use. “We’re also working on using robotics for some of our upcoming products.”

From a small Delhi office in 2011, ClearTax has moved to a large one in Bangalore after it received seed funding from Y Combinator and Mark Bell Ventures, and early funding from Sequoia Capital, followed by a $12 million round led by SAIF Partners in August last year. The company has raised $15.2 million till date.

In five years, ClearTax has taken a large share of the market, beating older players such as TaxSpanner, MyITReturns, Tax2Win, and TaxChanakya.

SAIF Partners principal Mridul Arora, who looks after the ClearTax investment, says that the company has scored over its competitors because of the “strong product and technology background” of its founders.

“Indians prefer to outsource their tax filing rather than do it themselves,” adds Vaibhav Sankla, managing director of H&R Block India, ClearTax’s competitor. H&R Block also has an online DIY tax-filing service, which it launched in 2014.

Sankla says the market for online tax filing itself is rather small. “About 22.5 million tax returns were filed in FY16,” he says. Sankla estimates the market is around 5 million returns.

To take care of such issues, ClearTax is diversifying its portfolio of services. It has ventured into aggregation and prepared a “highly curated” list of around 100 chartered accountancy firms looking for taxpayer customers. Also in the pipleline are products to help companies with the goods and services tax.

ClearTax is helping SMEs with complicated paperwork compliance and has launched a question-answer platform to help SMEs and freelancers file tax returns easily. It will soon launch another to help individuals make tax-saving investments. “Fintech is a sector that everyone wants to be in,” says Gupta. In that race, ClearTax has taken pole position.