Trustpilot has said it removed more than two million fake or harmful reviews over the past year.
The business-review site said the vast majority were dealt with by automated software without human involvement.
This marks the first time the Danish company has published a transparency report in its 14 year history.
It comes at a time it is reportedly preparing to list its shares, and the wider online review sector faces a regulatory probe.
“It is important that online sites take proactive measures to prevent fake reviews infiltrating their sites so that consumers can trust the information presented to them,” said Rocio Concha, director of policy at consumer group Which?.
Trustpilot allows the public to score and leave feedback about their experiences with organisations whose services they have used.
It makes money by selling services to the same businesses, helping them send review invitations to customers among other features.
BBC Watchdog and BBC Radio 5 Live, among others, have highlighted cases of companies cheating Trustpilot’s system by either getting genuine negative reviews removed or paying for positive ones.
However, in recent years the firm has made efforts to tackle such activity, most recently switching to leaving flagged reviews online until it has completed an investigation.
The transparency report seeks to show its safeguards are working.
It says of the 39 million written reviews posted to its platform in 2020:
2.2 million were removed for being fake or harmful, representing 5.7% of the total
1.5 million were automatically deleted by its fraud detection software
just under 660,000 were taken down manually
businesses reported about 469,000 suspicious reviews, of which 62% were taken offline
consumers reported nearly 90,000 suspicious reviews, of which 12% were removed
The firm’s chief trust officer told the BBC that machine learning techniques had helped it spot bogus posts that might otherwise have been missed.
“It’s very difficult for humans to spot a fake review [unless they are] badly done,” said Carolyn Jameson.
“But the machines look at multiple data points, like the number of times an IP [internet protocol] address has posted a review in quick succession, and patterns in language that might look natural to the human eye but have been repeated too many times in other reviews by the same person.”
She explained the large discrepancy between actions taken on business complaints versus consumer ones as being the result of other companies having more insight into the issue too.
Trustpilot announced in November that it was generating more than $100m (£72.2m) in annual sales for the first time.
Reports in the financial press followed that it was planning to float its shares.
But one potential hurdle is the UK’s Competition and Markets Authority’s launch of a probe into whether major websites are doing enough to crack down on fake reviews.
The watchdog has not mentioned Trustpilot by name, but given the firm’s size and influence many expect its activities will come under review.
And there may be suspicion that, by charging businesses to send out review invitations and reminders, it might be helping them skew their scores.
“Infuriated customers find Trustpilot and write a scathing review. Satisfied customers, if not prompted, will not bother,” said Francois Godard from Enders Analysis.
“The underlying problem is, specialised sites like Trustpilot… are stuck in a conflict of interest: to generate audiences they need to host critical, credible voices; to keep clients they need positive reviews and ratings.”
Trustpilot acknowledges companies that regularly ask customers for reviews tend to have higher star ratings.
But it says there is only a small difference in scores between those paying it to send invitations and those businesses that are active but using a free plan.
According to the transparency report the former has an average of 4.38 stars out of 5 and the latter 4.39.
“We welcome any interest in this area by regulators,” added Ms Jameson.
“[We’d be] very happy if the review sector as a whole can be a safe and secure place for people to come and find information.”