CHROME was once an underdog browser now labeled ‘spyware,’ ‘monopolist’. When Samuel Maddock built a browser that lets friends watch an online video at the same time, he used what seemed like the cheapest and simplest option: Chromium, a free, open-source version of Google’s Chrome Web browser.

“You have these gatekeepers like Google that decide which projects can work and if you’re not granted that permission you’re screwed,” Maddock said.

Google products have been as successful as Chrome. Launched in 2008, it has more than 63% of the market and about 70% on desktop computers, according to StatCounter data. Mozilla’s Firefox is far behind, while Apple’s Safari is the default browser for iPhones. Microsoft’s Internet Explorer and Edge browsers are punch lines.

Google won by offering consumers a fast, customizable browser for free while embracing open Web standards. Now that Chrome is the clear leader, it controls how the standards are set. That’s sparking concern Google is using the browser and its Chromium open-source underpinnings to elbow out online competitors and tilt entire industries in its favor.

Most major browsers are now built on the Chromium software code base that Google maintains. Even Microsoft is making the switch this year. That creates a snowball effect, where fewer Web developers build for niche browsers, leading those browsers to switch over to Chromium to avoid getting left behind.

This leaves Chrome’s competitors relying on Google employees who do most of the work to keep Chromium software code up to date. Chromium is open source, so anyone can suggest changes to it, but the majority of programmers who approve contributions are Google employees, and any major disagreements get settled by a small circle of senior Google employees.

Chrome is so ascendant these days that Web developers often don’t bother to test their sites on competing browsers. Google services including YouTube, Docs, and Gmail sometimes don’t work as well on rival browsers, sending frustrated users to Chrome. Instead of just another ship slicing through the sea of the Web, Chrome is becoming the ocean.

“Whatever Chrome does is what the standard is, everyone else has to follow,” said Andreas Gal, the former chief technology officer of Mozilla.

“We take it seriously, the responsibility of being good stewards of the Web,” said Darin Fisher, a vice president of engineering on the Chrome team. Google’s business relies on the Web working for as many people as possible, so the company doesn’t have an interest in squashing competition, he said.

Even if it isn’t trying to sabotage competing browsers, Google has a financial motivation to dominate the market, Gal said. He now works at Apple after selling his startup Silk Labs to the iPhone maker in 2018.

“In the past, there were these three, four major players with somewhat equivalent share between Microsoft and Google and Mozilla and Apple and nobody had this very clear advantage,” he said. “Today, especially in the desktop space, Google is definitely a monopolist.”

Earlier this month, Google announced a long-awaited decision on how Chrome handles online tracking software known as cookies. Other browsers have blocked third-party cookies by default, but Google chose to let users decide — and due to its dominance that will likely be the standard going forward. Shares of Criteo SA, a digital ad company that relies on cookies, jumped almost 10% on the news, the biggest gain in over a year.

“Chrome has become spyware,” said Brendan Eich, co-founder of Mozilla and the current CEO of Brave Software Inc.

Brave offers a browser that blocks ads and Web tracking software, and it is developing a system that pays users small amounts when they visit certain sites. This could upend the internet advertising business. The only catch is that the Brave browser is built on Chromium.

Even when people choose to download a competitor to Chrome, Google has ways to encourage them to come back. Vivaldi, a popular browser for the privacy-conscious crowd, has had trouble when it comes to running Google services like Docs and Gmail, said CEO Jon von Tetzchner. Some users logging into Google products on Vivaldi get prompt saying their browser isn’t optimized for them or suggesting they download Chrome instead.

Winning the browser war has done a lot more for Google than just allow it to create a friendly space for its other Web services. When Chrome users are logged-in to a Google account, the company can follow them around the Web, cataloging what sites they visit. All the data help Google’s ad products improve.

Fisher, the Chrome executive, said the Web needs advertising to keep it affordable for people who might not be able to pay publishers and other website owners for access.

“Chrome is independent of the ads group, but of course we collaborate with them, we both have a shared goal of a free and open Web,” Fisher said.”Part of making the Web really great is that there’s a diversity of content for users to consume.”

Diversity of browsers is another matter. If Microsoft, the world’s largest software maker, needs Chromium, it’s hard to imagine Google losing its grip any time soon.