Twitter’s blue check mark was loved and loathed. Now it’s pay for play.

Brian Stelter has long relied on the little blue check marks as key to reporting when news breaks.

The former CNN anchor would scan Twitter for accurate information from verified accounts about a developing tragedy or natural disaster or big event, then send them along to his producers for further follow up.

“That doesn’t mean you rush right to air with it necessarily, but it made a huge difference,” said the former host of “Reliable Sources.” He said that Twitter verification gained a cultural meaning, indicating who the messenger of the information was.

“It became shorthand for ‘we know the identity of that source,” he added.

On Saturday, that all changes. Twitter said last week it will begin removing legacy badges, instead reserving the blue check marks for paying customers.

“On April 1st, we will begin winding down our legacy verified program and removing legacy verified check marks,” the company tweeted.

Those paying roughly $8 a month for Twitter Blue, which includes a handful of other features, will also be among the small subset of accounts boosted starting April 15 to Twitter’s main timeline, the “For You” page. Twitter now requires a valid phone number and payment to attain the blue check, betting that spammers will not shell out large amounts of cash to flood the site with scams.

It was not clear whether all accounts will lose their verification or if some may be grandfathered in. Twitter could also delay the timeline for the rollout. News organizations including the New York Times, the Los Angeles Times and The Washington Post said Thursday they won’t pay for verification for their organizations or reporters, although the New York Times said there may be some rare exceptions.

Twitter CEO Elon Musk and Twitter did not respond to requests for comment.

Musk said on a Twitter Spaces Friday that he aims to make Twitter “the most trusted place on the internet.”

The massive changes to Twitter’s verification system risk disrupting the site, according to two former employees, who spoke with The Post on the condition of anonymity for fear of retribution. Twitter has repeatedly incurred outages after making tweaks to its code, including this month, something that has prompted Musk to refer to the site as “brittle.”

Meanwhile, the company has had only a loose handle on the interplay between old and new check marks. After a surge in impersonation accounts in November, when the company began awarding check marks to those willing to pay $8, Twitter employees were not immediately able to distinguish legacy verified check marks from those newly awarded, The Post reported.

The removal of verification badges at such a wide scale has the potential to disrupt systems across Twitter’s website, including its recommendation algorithms, spam filters and help center requests. Twitter has previously relied on the badges as an important signal affecting all of those areas - for example, using verification to decide to boost a public figure’s tweet into a user’s timeline.

Removal of verification badges is a largely manual process powered by a system prone to breaking, which draws on a large internal database - similar to an Excel spreadsheet - in which verification data is stored, according to the former employees. Sometimes, an employee would try to remove a badge but the change wouldn’t take, one of the former employees said, prompting workers to explore workarounds. In the past, there was no way to reliably remove badges at a bulk scale - prompting workers tackling spam, for example, to have to remove check marks one-by-one.

“It was all held together with duct tape,” the former employee added.

Musk has already struggled with an increased number of outages since his $44 billion takeover last year, troubles that have been compounded by his cutting more than two-thirds of the staff. And earlier attempts to roll out a paid verification system went awry.

The change expected Saturday could fundamentally change how Twitter is used and how it is trusted, users and experts say. If the fears are borne out, it will no longer be possible to quickly ascertain whether a public figure’s account is legitimately associated with that person, or the potential work of a sly impersonator. The perceived hand-wringing among the elite over the loss of the blue check - and its associated prestige - is a separate matter.

“I go onto Twitter and I interact with the blue check, and in my head I still assume they were verified out of some sort of process,” said Robyn Caplan, a senior researcher at the Data & Society Research Institute who is studying verified badge systems across social media companies. “There’s going to be a period of adjustment, and I think it’s going to be a much longer period than we think.”

The blue check mark on Twitter was first launched in 2009 as a way for the company to cut down on impersonation accounts, especially for celebrities. It grew over time to include thousands of verified accounts, ranging from government agencies to CEOs to athletes and movie stars to members of the media. The check mark has at times been decried as just another status symbol, a way for people to earn clout. But it’s also been used to confirm that account holders are indeed who they say they are.

Actor William Shatner has openly criticized Twitter for the decision, tweeting at Musk, “Now you’re telling me that I have to pay for something you gave me for free?”

“It’s more about treating everyone equally,” Musk responded. “There shouldn’t be a different standard for celebrities imo.”

In an interview, Shatner said he is concerned about possible impersonators that could pop up and use his name, paying for a blue check mark to make themselves look real.

“I want to stay on it but I want to be sure that it’s my voice, and my thoughts that people are hearing and reading, and not somebody who … wants to harm me in some way,” he said. Shatner will stay on Twitter without a check mark until he sees what “guardrails” the company introduces, he said.

Twitter initially launched the paid blue check mark in November, shortly after Musk took over the company, and had to quickly roll back the feature after impersonation accounts popped up all over the site, causing confusion. One account, purporting to belong to drugmaker Eli Lilly, tweeted that insulin would now be free. (It was not Eli Lilly, and insulin is not free.)

When Twitter relaunched the service in December, it put in rules banning impersonation and requiring a valid phone number before users could get a blue check mark. But a Post columnist showed that it was possible to get around Twitter’s defenses, obtaining a check mark for an account impersonating a U.S. senator. And some experts say that verification does not go far enough to confirm identities - prompting a reckoning for the future of the site.

“For the past decade Twitter was the watering hole where world’s most interesting people could huddle together and rub shoulders,” said Matt Pearce, an internet culture reporter for the Los Angeles Times. “But now the place is collapsing slowly, it’s like dying in front of our eyes.”

He said he won’t pay to subscribe.

Twitter has introduced different check mark colors for different accounts - including gold checks for organizations and gray checks for government officials.

On Thursday, the company outlined its process for verifying organizations - such as government agencies and businesses - linking to a sign-up form. Twitter said the organizations will be vetted to ensure they are legitimate, and once approved, those entities will be responsible for verifying affiliated accounts. Those verified under the process would receive a badge showing the organization’s logo, Twitter said.

“Rather than relying on Twitter to be the sole arbiter of truth for which accounts should be verified, vetted organizations that sign up for Verified Organizations are in full control of vetting and verifying accounts they’re affiliated with,” the company said in a tweet.

“Important to establish whether someone actually belongs to an organization or not so as to avoid impersonation,” Musk said in a tweet.

Twitter has been in a state of upheaval since Musk, who is also the CEO of Tesla and SpaceX, purchased the site he uses to communicate with his roughly 133 million followers on the site. The self-described “free speech absolutist” has said he wants to promote “free speech” and further Twitter’s role as a public town square.

When Musk first introduced the paid check mark, he positioned it as a way to make a more egalitarian site.

“Twitter’s current lords & peasants system for who has or doesn’t have a blue check mark is b------t,” he wrote. “Power to the people! Blue for $8/month.”

Musk announced Twitter had released its source code for recommendations on Friday, the computer code that generates tweets for its “For You” page. In his Twitter Spaces live audio chat, Musk said the decision was aimed at building trust.

“The goal with open sourcing the Twitter algorithm is to build trust and transparency with users,” he said. “We’re trying to make Twitter the most trusted place on the internet … to make it the least gameable system on the internet is our goal.”

Musk said that while the release of the code could prove “embarrassing” at first, his efforts were geared toward achieving the maximum amount of “unregretted user minutes” on the site.

But the rollbacks of legacy verification and other guardrails have some concerned. A Washington Post analysis this week found that Twitter is amplifying hate speech in its “For You” feed, based on which users accounts follow.

The changes are prompting concern among some who rely on the site, but don’t want to pay for it.

Emma Grae, a Scottish author with more than 13,000 followers on the site, said she expects her account will stop growing when she loses her verification check.

“It’s so frustrating too, as the old verification system has given me a lot opportunities with my writing - such as being asked to do talks about the Scots language - and I fear that I won’t get those chances now that I can’t prove I am who I say I am,” she said in a Twitter message.

Grae does not plan to pay for a check mark, saying that it seems like a way for Musk to recoup some of his investment and “in the process, he’s turning check marks into a bit of a joke,” she said.

For Shadi Hamid, a senior fellow at the Brookings Institution, the conversation he sees online about whether to give Musk money is a kind of “virtue signaling,” he said.

“It’s a service like any other and we pay for subscriptions, we pay all these companies and they do things we object to,” he said. He said he’ll evaluate how useful Twitter Blue seems to be before deciding whether to subscribe.

Others are still undecided. Author and YouTuber Hank Green, who has 1.5 million followers on the site, says he’s not worried about “the little blue tick going away,” but he wants his tweets about his charity to continue to reach the highest number of people they can. If it means boosting that reach significantly, it might be worth it to pay.

“But there are people for whom they would like to be part of the conversation, but can’t just willy-nilly add another $100 a year subscription to their budget,” he said.

Some account holders are taking the news of losing their blue check mark with a sense of levity.

“Rumor has it, we’ll lose our legacy blue check tomorrow,” the Seattle Public Library tweeted Friday evening. “That means there will be nothing left to stop you from impersonating us and aggressively telling your followers to get a Library card.”