Some Microsoft employees have used their company's own platform to support Chinese tech workers who are expected to carry out 12-hour workdays with just one day off a week.
In March, tech workers in China first published the "996.icu" project, aimed at highlighting the sector's "grueling and illegal" work schedule. 996 stands for 9 a.m. to 9 p.m., six days a week, while the ICU refers to the possibility of ending up in the intensive care unit of a hospital due to exhaustion.
The project is a collection, or repository, of alleged evidence of long hours and wrongful working conditions.
Despite such long hours being officially illegal in China, Alibaba founder Jack Ma has previously hailed the 996 culture as a "huge blessing" for the country. However, it seems his appetite for extended work is now being met with resistance from outside China.
On Monday, software engineers from Microsoft, Google, Facebook and others signed a letter of support for Chinese workers. The online letter was added to the 996.icu project on the web-based code-sharing service, GitHub.
The letter, co-signed by 100 tech workers, says that the workers of Microsoft and GitHub "stand in solidarity with tech workers in China." It also warned that Chinese internet firms are already attempting to censor the protest.
"Since going viral, Chinese domestic browsers, such as those by Tencent and Alibaba, have restricted access to the 996.icu repository on their web browsers, warning users that the repository contains illegal or malicious content." Spokespersons for Tencent and Alibaba were not immediately available for comment when contacted by CNBC.
Microsoft bought GitHub in 2018 for a reported $7.5 billion and the employees call on the two firms not to remove the content.
"We must entertain the possibility that Microsoft and GitHub will be pressured to remove the repository as well," it read. A spokesperson for the Washington-based firm also wasn't immediately available when contacted by CNBC.
As a sign of wide support, 996.icu has been "starred" by GitHub readers more than 230,000 times, making it one of the most popular repositories in the site's history.