For all the criticisms directed at the largest tech companies in the last couple of years, few smaller rivals have been willing to speak up publicly.

That changed for a couple of hours on Friday, as executives at four businesses pleaded with federal lawmakers to rein in Google, Facebook, Apple and Amazon.

At a congressional hearing in Boulder, Colo., top executives of Sonos, PopSockets, Basecamp and Tile testified that the biggest technology companies hindered their businesses. Their stories varied, but they shared a theme: The tech giants have used their powerful positions in search, e-commerce, online ads and smartphones to squeeze out them and other rivals.

Tile, which makes small tracking devices, said Apple had put up hurdles for Tile’s smartphone app that didn’t apply to Apple’s competing product. Sonos, the high-end audio company, said Google had copied its patented speaker technology and used its dominance in search to enter new markets. PopSockets, which makes smartphone grips, said Amazon “bullied” it into sales agreements and ignored complaints about counterfeits on the retail platform.