Alexandra Tweten was in her 20s when, like thousands before her, she signed up for online dating.

She was just looking for a decent guy.

What she also found was a world of abuse and harassment as men, feeling spurned by rejection, lashed out in the most vile way they knew how.

Warning: This article contains graphic and offensive terms.

"A lot of guys take the fact they think they're anonymous online to be more bold and say things they wouldn't normally if they saw you in person," she said.

Ms Tweten decided to fight back, taking screenshots of the abuse and uploading it to her Instagram account, @byefelipe.

It wasn't long before other women joined the cause, and what started as a project between friends grew into an online movement.

Since launching in 2014, @byefelipe has received more than 4,000 submissions from around the world — including Australia — and amassed more than 420,000 followers.

"The reactions I've gotten from a lot of women is them saying, 'Thank you for creating this and for giving women a voice'," Ms Tweten said.

"Because a lot of the time women said, 'I didn't know that other women went through this, I thought that I was the only one'.

"So it's kind of a sense of community and just understanding."

The posts cover all manner of harassment — from unsolicited nude selfies, to blunt demands for sex, and expletive-laden retorts when their advances are knocked back.

Ms Tweten isn't the only one naming and shaming the abusers.

Another Instagram account, @tindernightmares, shares similar screenshots, while @instagranniepants takes the comments and turns them into cartoon depictions of the men and their messages.

Why are people sending this abuse?

In some cases the hostile responses can be traced back to a heady mix of gender stereotypes and expectations, says RMIT research fellow Anastasia Powell, who specialises in policy concerning violence against women.

Dr Powell said people often tried to save face when rejected and that in modern society it was more socially accepted for men to express anger as an emotional response than to reveal sadness or vulnerability.

"On top of that, modern dating is still subject to a lot of gender stereotypes about how 'good' or 'proper' men and women are meant to behave, and how sex is meant to be negotiated," she said.

"According to the last National Community Attitudes Survey on Violence Against Women, a lot of Australians still believe that men should be in control in relationships.

"So for some men who hold those attitudes, being rejected in a dating situation might really go against their idea of how 'good' women are meant to behave."

The abuse isn't just isolated to a few examples, either.

A study by the Pew Research Centre in 2013 found 28 per cent of online daters reported being harassed or made to feel uncomfortable on a dating site or app.

Women (42 per cent) were far more likely to be on the receiving end than men (17 per cent).

In Australia, a 2015 survey of 3,000 Australians by RMIT and La Trobe universities found that while overall men and women were just as likely to report experiencing digital harassment and abuse, women reported higher levels of sexual harassment.

It also found that women "overwhelmingly" experienced harassment from men, while men received it equally from males and females.

It is just online? What can be done about it?

Dr Powell said it was a trap to think the abusive behaviour was limited to online interactions.

"In fact, women receive harassing and abusive responses from some men in a lot of other situations — in the street, in the workplace, on dates, every day," she said.

"The main difference I see with online abuse, is that women are able to screenshot it and share it. It's more visible, it can be proven."

The major dating sites are all trying to tackle the issue in some form or another, and each has some version of blocking and reporting abusive users as well as teams of moderators.

They often provide advice to users about how to stay safe online and before meeting up with strangers.

Sorry, this video has expired The world of online dating in 2018 ( Madeleine Morris )

Still, the onus is often put back on the user.

"Keep your communications limited to the platform and really get to know users online/using the app before meeting them in person," reads the online advice for dating app Tinder.

"It's up to you to research and do your due diligence."

Research fellow and expert in cyberpsychology Tracii Ryan said Instagram accounts like @byefelipe and @tindernightmares also helped to challenge behaviour by highlighting it.

"[They] are doing just this, by encouraging victims to call out individuals who are engaging in this behaviour and publicly denouncing their actions," Dr Ryan said.

"This is similar to how the #MeToo movement shed a light on sexual harassment, and called for change.

"I think educative campaigns need to help people realise that there is a real person behind the text, and that their words can have real consequences."