San Francisco: Explosive charges at Uber are shining a bright light on what has for years been an unsettling reality in Silicon Valley: Women here say they routinely confront sexism and harassment on the job.

Earlier this week former Uber engineer Susan Fowler claimed her prospects at the company crumbled after she complained about her supervisor's sexual advances, sending shock waves through Silicon Valley and Uber, which at $US68 billion is the world's most richly valued private technology company.

Diversity consultant Joelle Emerson says the allegations sounded a wake-up call. For the last several days she has been advising tech executives on "engaging in specific actions to make sure their companies can learn from what happened here."

"Companies that are committed to building an inclusive culture are not burying their heads in the sand on this. They're taking it very seriously," said Emerson, founder and CEO of Paradigm, a strategy firm that consults with tech companies on diversity and inclusion. "If you're a CEO in Silicon Valley, and you haven't yet emailed your whole company, or at least your leadership team, about this, you're behind."

Hours after Fowler published a blog post detailing her experiences, Uber CEO Travis Kalanick opened an investigation led by Liane Hornsey, the company's recently hired chief of human resources, and former US Attorney General Eric Holder.

More recently Uber board member Arianna Huffington pledged to "hold the leadership team's feet to the fire."

"Change doesn't usually happen without a catalyst. I hope that by taking the time to understand what's gone wrong and fixing it, we can not only make Uber better but also contribute to improvements for women across the industry," Huffington said in a statement.

For all of its bravado about changing the world, the tech industry is very much a man's world, lagging behind other industries in its representation of and treatment of women.

Women use the latest apps and gadgets in equal, if not greater, numbers. They outnumber men at the top schools and in the workforce. But they are in short supply in Silicon Valley.

Seven out of 10 workers at major tech companies such as Google and Facebook are men. Women comprise 20 per cent or less of technical staff. Few women reach the senior executive level or the boardroom. And they don't fare much better as entrepreneurs. A sliver of venture capital funding goes to women and a small percentage of venture capital investors are women.

Since 2014, major tech companies have taken a big step toward facing up to the gender gap by publicly disclosing the demographics of their workforce. Uber has repeatedly refused requests to disclose such demographics. Kalanick now says Uber will release diversity numbers in coming months.

Studies warn that tech's gender gap is only widening as women are being held back by stereotypes, biases and work environments that make them feel marginalised, unwelcome or even threatened.

There's definitely an unofficial 'Yelp' out there that can never be silenced. We're keeping the receipts.

Arlan Hamilton

Six out of 10 women working in Silicon Valley experience unwanted sexual advances, according to a survey released last year. About two-thirds of these women said these advances were from a superior.

The only place women seem to be gaining representation is in the courts. In 2015, Ellen Pao lost her discrimination case against venture capital firm Kleiner Perkins Caufield & Byers. Last week Magic Leap was sued for sexual discrimination by an executive who was hired to help the augmented reality company hire more women.

"What is happening at Uber is, unfortunately, widespread in the industry," said Elissa Shevinsky, an entrepreneur, tech investor and editor of Lean Out: The Struggle for Gender Equality in Tech and Start-up Culture.

"When I set out to publish Lean Out, I asked women in tech to send me their stories. I was looking for cheerful stories. I was enjoying being a start-up CEO. But almost universally, these stories were about misbehaviour and exclusion," Shevinsky said. "That taught me a lot about the industry."

Arlan Hamilton, founder and managing partner of Backstage Capital, says "the major infractions" she has personally experienced and the stories she has heard from others are "out of this world."

Hamilton declined to discuss specific incidents.

Fowler, who's now working at San Francisco tech company Stripe, is one of the few women who have spoken out publicly. Many women feel they must stay quiet to keep their jobs or careers or because they have collected a settlement that prevents that from discussing what happened. Women who do come forward often have their accounts of sexism or harassment discounted. But, says Hamilton, behind closed doors women in tech talk to each other and they believe each other.

"There's definitely an unofficial 'Yelp' out there that can never be silenced," she said. "We're keeping the receipts."

And that's a major problem for the tech industry. Research shows diversity in the workforce — more women and more people of colour — is crucial to shaping 21st century technology. It's also vital that women and minorities gain equal access to one of the world's highest-paying careers in one of the economy's fastest-growing sectors.

Nothing short of a culture overhaul will root out sexism in tech's alpha-male culture and bring about real change, says Emerson.

"This is a cultural and systemic problem," she said. "The solutions must be structural and comprehensive."

Kate Losse was an early Facebook employee and author of The Boy Kings: A Journey Into the Heart of the Social Network.

"It's a shame that companies that do this don't realise they are losing great employees, sowing mistrust, and that no matter how much companies try to suppress these problems, employees know they are better off somewhere else," said Losse, who now writes about design and technology. "The pattern will just keep happening unless companies from the top down make serious, structural changes toward truly equitable treatment."

USA Today