Amazon was selling the merino wool sneakers for a third of Allbirds' $95 price on its platform, according to Bloomberg News.
Allbirds CEO Joey Zwillinger said his company is "flattered" by Amazon's imitation shoe product but hopes the tech giant will make more of an effort to use sustainable material for the sneakers as Allbirds does in an open letter published Monday to Medium.
"We are flattered at the similarities that your private label shoe shares with ours, but hoped the commonalities would include these environmentally-friendly materials as well. Alas, we're here to help," Zwillinger wrote.
"As we've done with over 100 other brands who were interested in implementing our renewable materials into their products, including direct competitors, we want to give you the components that would make this shoe not just look like ours, but also match our approach to sustainability," he continued.
Zwillinger said Allbirds, in collaboration with petrochemical company Braskem, created the first environmentally friendly foam used on the bottoms of sneakers and pointed out that Amazon's version uses an unsustainable foam.
"If you replaced the oil-based products in your supply chain with this natural substitute (not just for one product, but all of them), we could jointly make a major dent in the fight against climate change. With the help of your immense scale, the cost of this material will come down for all users of this material, allowing for even broader adoption," the Allbirds CEO wrote.
He added that Allbirds is "happy" to send Amazon a free sample of its sustainable foam material.
"Customers value companies that are mindful of the planet and profits, and we believe the most powerful businesses in the world, such as Amazon, should lead on these issues and will be rewarded for doing so," Zwillinger said.
Amazon has previously come under fire for selling private-label products that resemble designs by other companies. Williams-Sanoma sued the tech giant in 2018 for selling a furniture line with products that were "strikingly similar" to Williams-Sonoma's West Elm brand.
Amazon did not immediately reply to a request for comment.