Thousands of Reddit forums are going dark Monday in one of the largest user-driven protests ever to hit the social media platform.

The voluntary blackouts, which restrict groups' content from being publicly visible, affect Reddit's largest online communities, including popular groups devoted to music, history, sports, and video games. The protests include more than two dozen subreddits with at least 10 million subscribers, as well as thousands of smaller networks.

Monday's protests reflect widespread outrage over a Reddit plan to charge millions of dollars in fees for some third-party apps to continue accessing the platform. The plan has already forced several of Reddit's top app-makers to announce they are shutting down because they cannot afford the new costs, which are set to begin as soon as next month.

The confrontation between Reddit's corporate management and its users and developers marks a turning point for the platform as it reportedly looks to go public later this year. For years, Reddit users could browse posts, write comments and share pictures and video on Reddit from third-party apps.

Now, however, Reddit is seeking large payments from app makers to maintain that same level of access through its application programming interface (API), in a move apparently aimed at better monetizing Reddit users. Last week Christian Selig, developer of the popular Apollo app, said Reddit wanted to charge him $20 million a year to keep his app running. He later said he has no choice but to close down the app.

Reddit further inflamed tensions with some in its developer community by appearing to misrepresent the details of its private conversation with Selig to suggest he had blackmailed the company. Selig, however, recorded his phone call with the company, a fact Reddit co-founder and CEO Steve Huffman later acknowledged in a Q&A with users.

Selig's app is just one casualty of the coming changes. Critics of Reddit say the platform's steep fees will kill off all third-party competition against Reddit's proprietary app, which many users have derided as slow, buggy and inferior. They also fear the moves will decimate a volunteer community that relies on third-party tools to do the critical work of moderating Reddit forums — responsibility Reddit delegates to users of the site rather than to its own paid employees or to contractors, unlike some other large social networks.

Reddit's defenders, including some users, have said it is Reddit's right to set its own prices for API access, and that it is a business entitled to control how users access the data on the platform it provides. Some users have said they were not even aware it is possible to access Reddit from third-party apps.

"Reddit needs to be a self-sustaining business, and to do that, we can no longer subsidize commercial entities that require large-scale data use," Huffman wrote in a Q&A with users Friday.

The battle echoes how Twitter, under its new owner Elon Musk, recently announced its own paywall for data in a bid to develop new revenue sources and to shore up the company's struggling finances. Twitter's move prompted an outcry from third-party app makers, misinformation researchers and public service account-holders who said the move would harm transparency and accessibility. Twitter has responded to the criticism by adding a new tier to its paid plan, but the move was instantly blasted as too little, too late.

Now Reddit faces a similar revolt, one that may prove even more effective in light of its greater reliance on community members for the site's basic upkeep.

The stakes of the fight are not limited to Reddit alone. It takes place against the backdrop of a wider debate about who creates the value in social networks, and who gets to reap the rewards. And it reflects years of mounting public skepticism of large technology platforms that became economically dominant through the collection and exploitation of vast troves of other people's personal information.

For Reddit and its future shareholders, the company's value derives from the infrastructure the site provides for conversation. Operating that infrastructure, safeguarding what is stored there and charging for access to that proprietary data generates value that Reddit believes it should be able to keep.

For Reddit's developers and moderators, however, the platform's value derives not just from the company's operation of the platform but also in the user-led moderation of the site's countless forums, as well as the various tools and features that others have created to make Reddit more useable — for example, for the blind and visually impaired. Those solutions may not have been built by Reddit itself, but the company benefited from them in that they helped the site grow and reach wider audiences.

To a degree unlike Instagram or YouTube, Reddit owes its rise to the volunteer work of many of its users who bore the costs of developing features that the company did not see fit to invest in. In that respect, Reddit more closely resembles Wikipedia, the crowd-sourced digital encyclopedia whose volunteer editors are viewed as a vital resource.

Now, though, many users feel betrayed.

"If they're going to start charging for API calls, [moderators] should start charging reddit for their time keeping the website functioning," one user wrote. "This site ONLY functions on the backs of free labor from mods."

Some have vowed to stop using Reddit, and others have suggested they may even scrub their entire account so that the company cannot monetize their historical activity.

"For a large number of Apollos users, it's existence is the only reason we're still using the platform," another user wrote. "I've been here 15+ years, but have no intention of sticking around once Apollo goes dark."