A group of small tech firms told Congress that Google, Apple and Amazon used bullying tactics to try to crush them. Here are some of the most astounding stories they shared.

Earlier this month, Sonos sued Google, alleging that the tech giant infringed on five of its patents.

But Sonos CEO Patrick Spence's testimony against Google went far beyond that.

The advantages Google has in marketing its own products "are like nothing we've ever seen before," Spence said. For instance, Spence alleged that Google had pressured Sonos to only allow its speakers to sync up with Google Assistant, rather than also offer it on Amazon's competing voice assistant Alexa.

"Looking at leveraging market dominance to dominate another category has to be thought through. Is that the spirit of the kind of world we want to live in?" he later added.

Threats of retaliation were also of ongoing concern to the testifying companies.

"We could lose our listing in DuckDuckGo and we wouldn't even tell. We lose Google and we lose our business," PopSockets CEO David Barnett said.

Basecamp CTO David Heinemeier Hansson also had concerns on his company's presence on the search engine. Google makes up more than 40% of Basecamp's traffic, per Reuters, but it allowed competitors to buy ads on Benchmark's trademark and block consumers from reaching the site, Hansson said. The company could only compete by similarly buying ads on Google search.

"Sonos has made misleading statements about our history of working together. Our technology and devices were designed independently. We deny their claims vigorously, and will be defending against them," Google told Business Insider in a statement.

"For trademarked terms like the name of a business, our policy balances the interest of both users and advertisers. Like other platforms, we allow competitors to bid on trademarked terms because it offers users more choice when they are searching. However, if a trademark owner files a complaint, we will block competitors from using their business name in the actual ad text," Google said.

PopSockets, which makes phone accessories, accused Amazon of failing to remove counterfeit products and pressuring it to lower its prices. If it failed to do so, Amazon said it would source the same accessories from third-party sellers, PopSockets CEO David Barnett alleged.

Barnett said Amazon had a host of such tactics to "bully" businesses, and described informing Amazon about 1000 fake products every day, with no recourse. At the same time, Barnett said that Amazon was lowering the prices it was charging consumers, and then demanding payment from PopSockets for its lost marginal profits.

PopSockets has had a tense relationship with the online marketplace for years. The company eventually stopped selling on Amazon, as a result of counterfeits and aggressive pricing tactics, Barnett said.

He ultimately suggested that Congress break up Amazon into two bodies: one that runs the marketplace, and the other that sells on it.

"We sought to continue working with PopSockets as a vendor to ensure that we could provide competitive prices, availability, broad selection and fast delivery for those products to our customers. Like any brand, however, PopSockets is free to choose which retailers it supplies and chose to stop selling directly through Amazon," an Amazon spokesperson told Business Insider.

"Even so, we've continued to work with PopSockets to address our shared concerns about counterfeit, and continue to have a relationship with PopSockets through Merch by Amazon, which enables other sellers to create customized PopSockets for sale," Amazon said.

Complaints about Facebook were the most sparse out of the small tech company testimonies, and largely addressed data-privacy concerns rather than anticompetitive behavior.

Facebook has a "devastatingly effective" ad machine, Basecamp's David Heinemeier Hansson said. "But when you think about why everyone is unable to compete, it's because it's all based on a fundamental violation of privacy."

And when asked to respond to any concerns regarding Facebook's attempted launch of Libra, and the potential that it would turn into a huge bank, Hansson said that would be a "catastrophe."

"No single company should have access to this much data," Hansson said. "We already have problems dealing with the problems they've created."

Facebook declined to comment.