"Providing the Chinese government with ready access to user data, as required by Chinese law, would make Google complicit in oppression and human rights abuses," the letter created by Google Employees Against Dragonfly states.
"Our opposition to Dragonfly is not about China: We object to technologies that aid the powerful in oppressing the vulnerable, wherever they may be."
The group said that many of them joined the search giant because it was "willing to place its values above its profits", including its 2010 decision not to censor search results in China; however, it believes this is no longer the case.
"We also demand that leadership commit to transparency, clear communication, and real accountability. Google is too powerful not to be held accountable," the letter said. "We deserve to know what we're building and we deserve a say in these significant decisions."
Creating Dragonfly would set a dangerous precedent that would make it harder for Google to not build similar functionality in other countries, the group said.
In September, The Intercept reported that Dragonfly would require users to log in to search, track their location, and share data with a "Chinese partner".
Naturally, any Chinese search engine would come with the censorship and blacklists that are standard across the Chinese internet.
In November, WeChat, the popular messaging app operated by Chinese technology giant Tencent, had pledged to concentrate on cleaning up undesirable content from self-media on its platform to maintain a "healthy" reading environment as required by the government.
The content cleanup will specifically target harmful political information, pornographic and vulgar content, click-bait headlines, plagiarism, infringement, and other violations in order to provide users with a more healthy reading space, WeChat said.
Opinion: To sign up for Google's Advanced protection program, you must buy security keys from a Chinese vendor. Security questions have since been raised considering current intelligence laws in China.