"Dear Donald ... Your campaign doesn't just seem wrong. It feels un-American," says a full page ad in Sunday's newspaper.
It was paid for by Josh Tetrick, the entrepreneur behind the controversial Just Mayo product, a plant-based condiment that aims to unseat traditional mayonnaise.
His ad appeared in the New York Times and the Plain Dealer, a local paper in Cleveland where the Republican National Convention will take place this week.
Tetrick, the founder and CEO of food tech startup Hampton Creek, is protesting Trump's disrespect for women and minority groups.
"His campaign doesn't reflect basic American values," Tetrick told CNNMoney on Sunday. "We can disagree on a lot but there are certain things that everyone does agree with: You should respect women. Immigrants make this country better. We should be civil to each other. The KKK is a group that is the personification of evil. There are these basic things that we don't need to argue about."
Tetrick describes himself as a moderate democrat and said the ad, which only has 129 words including Tetrick's name, has struck quite a chord with Americans. (It can be read online, too.) While he didn't identify his company in the ad, Tetrick did leave his actual phone number for people to reach out.
He said he's received hundreds of calls, more than 600 voicemails, and is getting about ten text messages every minute from strangers around the country. They range from grandmothers to factory workers and "lots and lots of Republicans" praising him for speaking up. "98% have been heartfelt," he said, but a few have been unkind.
"You've said what a lot of us are thinking. As an immigrant woman who has been in this country for 30 years, for the first time, I'm so scared and really frightened. Thank you so much for having the guts to be able to say what you did for most of us who don't have a voice," said one Florida-based woman in a voicemail to Tetrick obtained by CNNMoney.
"I just wanted to call and express my deep appreciation for your expression to Donald Trump. You capture perfectly my own concern and worry about this proto-Facist element that's developed in our struggling democracy ... On behalf of my family, thank you," said a man from Arkansas.
Tetrick, who has raised more than $120 million from big name backers like Marc Benioff and Khosla Ventures, is no stranger to taking out ads in the New York Times, listing his name and number for the world to see. He generally targets the food industry.
Related: Tech leaders: 'Trump would be a disaster for innovation'
While there are reports that he paid hundreds of thousands of dollars for the ad, Tetrick said that couldn't be further from the truth. He declined to discuss specifics, but said "it's not even in the stratosphere of that."
Speaking out about Trump is in line with his company's mission of effecting change in the world, he told CNNMoney.
"I just had to get this out of my head so I could sleep better," he said. "It's too important."
Tetrick said that the recent death of Elie Wiesel and a quote from his book, "Night," was the big impetus for the ad campaign: "The opposite of love is not hate, it's indifference." His personal Twitter account and Hampton Creek's account both have pinned tweets of different Elie Wiesel quotes.
"I do think there is an obligation to say something," he added. "I hope that if you're a leader of a public company, I hope you say something."
The ad comes after 145 tech leaders penned an open letter to the world about Donald Trump, including execs from Google (GOOG), Facebook (FB), and Apple (AAPL) as well as startups, venture capital firms, nonprofits and universities.
The Donald Trump campaign did not immediately respond to CNNMoney's request for comment.
