Intuit's (NASDAQ:INTU) strong momentum persisted in its fiscal fourth quarter of 2019. The financial software company saw its top-line growth accelerate. Total revenue during the period rose 15% year over year, up from 12% growth in the prior quarter. This meant Intuit's revenue was well ahead of its own guidance and higher than analysts' forecasts.

For investors who want to get a better understanding of what's behind the tech company's accelerated growth rate, management provided some interesting insight into key growth drivers during its fiscal fourth-fourth quarter earnings call.

QuickBooks Online on a tablet

Image source: Intuit.

Online ecosystem revenue

Playing a key role in Intuit's success ever since the company launched an online version of QuickBooks has been Intuit's online ecosystem revenue -- a category that lumps together revenue from Intuit's online small-business and self-employed software.

Online ecosystem revenue increased 35% year over year in fiscal Q4, down slightly from 38% growth in fiscal Q3 but easily in line with management's ongoing target for 30%-plus year-over-year growth in the key metric.

Management continues to emphasize the importance of this revenue category.

"We believe the best measure of the health and success of our strategy going forward is Online Ecosystem revenue growth, which we continue to expect to grow better than 30 percent," said QuickBooks CEO Sasan Goodarzi.

Notable drivers for online ecosystem revenue included QuickBooks Online, payroll, and payments.

An acceleration in QuickBooks Online subscribers

One particularly encouraging trend in Intuit's fiscal fourth-quarter update was an increase in its QuickBooks' online customers.

"And with that said, I would actually say that when you look at our fourth quarter QBO, we did not moderate versus this time last year. And actually we accelerated our growth," Goodarzi pointed out.

Intuit's fiscal fourth-quarter QuickBooks Online subscribers climbed 33% year over year during the period -- a bump from 32% growth in its third quarter of fiscal 2019.

The CEO added, "So we feel good both around the customer growth in QBO, but more importantly the services that we are provide, and the fact that we believe that it will continue to allow us to grow north of 30% for our online [ecosystem] revenue."

Rapid growth in TurboTax Live

While much of the focus of Intuit's business is centered around its online ecosystem revenue these days, Intuit is seeing promising momentum in one of its newer TurboTax offerings: TurboTax Live. Launched in late 2017, TurboTax Live gives customers access to experts for help in filing their taxes.

So far, the service has proved to be a hit.

"TurboTax Live is now a meaningful contributor to our business, and compared to other Intuit product lines is among the fastest ever to reach this revenue level, " explained Goodarzi. "We feel great about the experience we delivered for our customers to drive increased confidence and the improved experience and operating efficiency we provided to pros on our platform."

More specifically, Intuit said it has tripled the number of customers using TurboTax Live compared to the year-ago quarter.