Boston College’s website somewhat understatedly describes its history professor Heather Cox Richardson’s Substack as having “a cult following”.

In fact, Letters From an American – which situates a day’s events within their historical context – is widely considered to be one of the most successful newsletters on the platform. Various estimates have put its author’s annual revenue from 1.2 million subscribers at anything between $1 million and $5 million (£800,000 and £4 million).

Although she was previously a respected but little-known academic who lives in Maine with her lobster fisherman husband, the site has also catapulted Professor Cox Richardson into the limelight; last year she was named “woman of the year” by USA Today.

Campus spotlight: Tips for success in academic publishing

Buoyed by such successes, Substack, which started as an email newsletter platform in 2017, has been targeting academics of late, offering a chance to build a profile – and sometimes a livelihood – away from institutional affiliations and prestige journals.

It says academics are one of the fastest-growing categories on its platform and, in the last year, paid subscriptions for UK-based academics have grown eight times faster than the year before, while free subscriptions have trebled.

Clyde Rathbone, partnerships manager at Substack, said he saw this as the early stages of what he predicted would be “aggressive growth”, particularly as scholars looked for new ways to share their work online as academic usage of Twitter declined.

“We think we are the perfect fit for the kind of work academics want to produce on the internet,” Mr Rathbone said. “We have academics who want to build media businesses or people who have decided a long-term career in academia might not be for them and want a more creative outlet. We have lots of people earning over six figures, a few well into the seven figures.

“For others it is not their full-time professional focus, but they want a secondary income stream or to reach a new audience. I think it will get to the point where it is unusual for an academic not to have a Substack.”

Even academics who work in very niche areas could “build a very powerful business”, Mr Rathbone said, because they now had direct access to the “few thousand people on the planet who care deeply about the subject and will pay the equivalent of a cup of coffee a month” to read about it.

University of Kent politics professor Matt Goodwin has been one of those building an audience on Substack after being approached to bring his writing to the platform in the summer of 2022.

In that time he has grown his subscriber numbers from 6,000 to 20,000, attracting readers with his political insights and criticism of so-called cancel culture; one of his most popular posts is a copy of a speech he gave to the controversial National Conservatism Conference that was held in London earlier this year.

For Professor Goodwin, it is not income but influence that he feels he gets from his site. “I have two former prime ministers on the list, a former leader of the Labour party, MEPs, MPs, No 10 people, quite a few academics and lots of members of the public,” he said.

“It is primarily people who are very interested in politics but want to go further than what they read in the newspapers. You are able to build an ongoing conversation with your audience and tell a story over a much longer period of time.”

Professor Goodwin said he saw Substack as a tool used by an “increasingly hybrid model of academic”, who split their time across university, policy and media work, but he would be wary of going “all in”.

“For me the jury is still out on the funding model. You might have people prepared to pay £5 a month to read what Professor X has to say but not willing to pay £50 a month to read what 10 professors have to say,” he said.

For this reason, Professor Goodwin said, collective Substacks – where academics with similar expertise club together to create a single page – might be a more viable long-term option.

“It may be in the future that I decide this is the only thing I want to do, but my personal view is you can’t really be credible in the marketplace of ideas unless you are producing the books and research as well,” said Professor Goodwin.

“If I was only doing Substack I don’t think people would take me particularly seriously. Unless you have a backbone of research then I think it is hard to cut through in a major way.”

Rachel Botsman, another academic with a large Substack following, agreed, although she last year chose to leave a faculty role at the University of Oxford’s Saïd Business School to focus on writing and public speaking full-time.

“I think it is easy to say universities have had their day and academics need to do it differently, but they definitely still have a role. I spent 10 years developing a body of work before I could really go out and be independent,” she said.

“If I am honest, I realised teaching is my passion and university life and the system of academia wasn’t for me.

“It’s very easy to get locked into writing things and publishing things for the next rung on the ladder versus what you really want to give to the world, what you really want to develop.”

After graduating from Yale University and the University of Cambridge, psychologist Rob Henderson also turned away from a traditional academic career and, after building a profile elsewhere, was brought to Substack by an offer of a “pro deal” – a one-year contract to write for the platform, for which he was paid $100,000. These deals are no longer offered by Substack.

Dr Henderson says his annual Substack gross income is now closer to $140,000 a year, which “gives me a degree of independence that can be beneficial for pursuing my own interests and projects”.

Of 40,000 total subscribers, 1,865 pay $9 a month or $79 a year, which gives them access to paid posts and the opportunity to take part in “ask me anything” threads. Eight subscribers have become “founding members”, paying $500 a year.

Readers can also book meetings with Dr Henderson via Substack – at a cost of $300 for 30 minutes – and he said the slots filled very quickly, with 40 of these meetings held already this year. Most want to discuss the topics he writes about – psychology, dating apps, class divides and social mobility – but others want to talk about how to launch a successful newsletter.

He allocates 60 hours a week to his work, including time to read, think, take notes and brainstorm. The actual act of writing and editing the posts takes about 10 hours a week.

Dr Henderson does cite and link to relevant research in his posts, but he said they should be read in the same way as magazine articles or newspaper op-eds and not as if they were in peer-reviewed journals.

For Ms Botsman, Substack provides the opportunity to present “ideas in their infancy”.

“I think most academics would baulk at sharing stuff until it is absolutely watertight. That is not the way I think or operate. It is a different philosophy to developing ideas and bringing them into the world,” she said.

“My goal isn’t to make loads of money; it is to use it as an ideas laboratory. So I put ideas out there that are in development, and I can see from the response if there are real legs to it. When you have a piece going well, you can just see it. And you can dig in a bit more to see what’s resonating with people and build on it.”

This role in an academic’s thought process is where Substack can be an “incredibly powerful tool”, said Professor Goodwin, and might, in future, affect the relationship between academics and publishers.

“I do wonder if over the longer term Substack is increasingly used by academics as a way of disseminating research and writing in a way that circumvents traditional publishers,” he said.

“We are going to have to wait five to 10 years to see how that evolves, but I can certainly see how that raises a whole host of difficult questions for established practice in academia.”

Does this freedom to publish come at a cost? Analysis by Press Gazette earlier this year found that some of the most lucrative accounts on Substack are owned by Covid vaccine sceptics and others with fringe views who have effectively used the platform to monetise and disseminate their extreme opinions to a large audience.

While far from conspiracy theorists, both Professor Goodwin and Dr Henderson are well-known oppositional voices within higher education, both frequently criticising what they see as the politicisation of universities and the rise of academics being “cancelled”.

Does Substack suffer from the same outrage-economics as social media, where clicks and engagement often depend on being outspoken?

Professor Goodwin agreed he had become much more critical of the direction of universities but said the platform instead offered a chance to have a more nuanced discussion.

As an example, he cited a recent post dissecting his role advising on the development of England’s new Higher Education (Freedom of Speech) Act, which he used to “tell the story of how we responded to that challenge”.

“When universities lean so strongly in one direction, I feel a responsibility to raise points that others might not raise. We’re not all here to agree and have a stifling orthodoxy imposed on us. There are lots of good reasons to be critical.”

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Stacking up: academics with big followings on Substack

Katelyn Jetelina: Your Local Epidemiologist
205,000 subscribers
Former University of Texas assistant professor provides insight into public health science

Richard Dawkins: The Poetry of Reality
20,000 subscribers
Evolutionary biologist brought his writings on religion and the natural world to Substack in June

Emily Oster: ParentData
203,000 subscribers 
Economics professor at Brown University takes an evidence-based approach to parenting

Asha Rangappa: The Freedom Academy
25,000 subscribers
Senior lecturer at Yale University’s Jackson Institute for Global Affairs and a former FBI special agent teaches a course on Substack on misinformation

Sam and Lawrence Freedman: Comment is Freed
37,000 subscribers
Emeritus professor of war studies at King’s College London and his former government adviser son provide their take on policy and foreign affairs

Tim Spector: Gut Feelings
5,000 subscribers
King’s College London genetics professor on what the latest science says about improving your health

Adam Tooze: Chartbook
99,000 subscribers
Columbia University professor writes on economics, geopolitics and history

Jacqueline Nesi: Techno Sapiens
19,000 subscribers
Psychologist and professor at Brown University shares research on parenting, social media and mental health