WASHINGTON — After lawmakers collected hundreds of hours of interviews and obtained more than 1.3 million documents about Amazon, Apple, Facebook and Google, their chief executives will testify before Congress on Wednesday to defend their powerful businesses from the hammer of government.

The captains of the New Gilded Age — Jeff Bezos of Amazon, Tim Cook of Apple, Mark Zuckerberg of Facebook and Sundar Pichai of Google — will appear together before Congress for the first time to justify their business practices. Members of the House judiciary’s antitrust subcommittee have investigated the internet giants for more than a year on accusations that they stifled rivals and harmed consumers.

The hearing is the government’s most aggressive show against tech power since the pursuit to break up Microsoft two decades ago. It is set to be a bizarre spectacle, with four men who run companies worth a total of around $4.85 trillion — and who include two of the world’s richest individuals — primed to argue that their businesses are not really that powerful after all.

And it will be a first in another way: Mr. Zuckerberg, Mr. Pichai, Mr. Bezos and Mr. Cook will all be testifying via videoconference, rather than rising side-by-side for a swearing-in at a witness table in Washington. Perhaps appropriately, their reckoning will be broadcast online.