The 19 most interesting ad-tech upstarts of 2017, ranked

• Ad-tech funding has dried up and the IPO market is quiet.
• But there are many companies making waves, particularly startups focused on marketing data, brand safety, and the future of TV ads.

In ad tech, things have changed.

You can see it in the slowdown in VC funding. The growing power of Google and Facebook has shaken up the market. Many saw the recent $125.5 million sale of Rocket Fuel, which was once valued at $2 billion, as the end of an era in ad tech.

So this year, we're rethinking our hottest pre-IPO ad-tech ranking. We stretched the definition, going beyond companies purely anchored in the programmatic-ad sector to include startups that help big marketers make sense of their growing piles of data, a massively important area with loads of opportunity going forward.

We've also included firms looking to shape the future of video and TV advertising, where software and algorithms have barely scratched the surface of what they can achieve.

The future of digital advertising will surely be messy and uncertain, but also ripe for entrepreneurs with disruptive ideas.

"While we believe many digital startups will suffer as the ecosystem rationalizes and consolidates, there is always room - and great exits - for innovative companies with scale and differentiation," said Terence Kawaja, founder and CEO of Luma Partners, a strategic advisory company.

Methodology

This list is a ranking of companies in the nebulous "mad-tech" space, which includes ad-tech companies, marketing-tech firms, marketing-data and -analytics companies, and some startups in between. We took into account how big these companies are, how much revenue they pull in, how much they've raised, who they work with, and their reputations.

But we also looked at whether companies are solving existing problems (how to make a few more cents on banners ads, how to plug into dozens of ad exchanges) or are taking on new challenges. We talked to lots of publishers, ad buyers, ad-tech employees, and investors to figure out which companies should be here and, perhaps more important, which shouldn't.

We also thought this list should accurately reflect the disarray in ad-tech. That means that some large-headcount, large-revenue companies were penalized in part because they've raised lots of money and oriented their businesses around display ads and a 1.0 desktop web.

Meanwhile, we gave credit to companies that, while perhaps not as large or who haven't raised as much, are still at the center of important trends. They're helping solve brand safety, identity, managing varied data streams or measurement - and are less about just delivering targeted ads programmatically.

We threw in some curveballs. While we kicked off companies that have gone public or gotten acquired (sorry, Trade Desk and Moat), we've included a few startups born in traditional media companies. So we're making our own rules here.