There was a time when employees at Apple—long one of Silicon Valley’s most secretive companies—wouldn’t dare to speak openly about their employer in public without permission. Often they were too spooked to talk to colleagues in other parts of the company, if they could even figure out who they were.

But in the past few weeks the doors to the Apple kingdom have been partially cracked open with the help of an unlikely tool: Slack.

The popular messaging tool became a hit at the 160,000-person company during the pandemic, when many employees were forced to work from home. And in recent months, Slack has become a virtual town square. They have rallied there to protest the company’s plan to return to its offices, object to its method of granting exemptions for continued remote work and declare their outrage over Apple’s hiring of a controversial tech industry figure.