A who’s who of technology and media heavyweights, including Ashton Kutcher, Bill Gates, Twitter co-founder Ev William and entrepreneur Richard Branson, have joined a $25m (£16m) funding round in the social activism platform Change.org.

The funding round also includes LinkedIn’s co-founder Reid Hoffman and chief executive Jeff Weiner, Yahoo co-founder Jerry Yang, Huffington Post’s Arianna Huffington and A-Grade Investments, the venture capital firm founded by actor Kutcher, Guy Oseary and Ron Burkle.

Omidyar Network, the philanthropic investment firm created by eBay founder Pierre Omidyar ,which led a $15m funding round in Change.org a year ago, has also “significantly increased” its investment in the latest fundraising.

“We wanted two groups of people on board as we expand globally,” said Ben Rattray, founder and chief executive of Change.org. “The first is founders and chief executives of the world’s largest internet companies who know how to build at scale. The second was leaders in business and media because ultimately those are the avenues that some of the biggest change happens.”

Rattray said the founding team were still in control of the company, and that the latest investors to be approached have been selected because they are “mission-aligned” with Change.org’s strategy.

“To think long-term and make the best decisions in the interest of the company it is important for investors to have input but not control,” he said. “It is important for us to retain independence. There are much easier ways to raise $25m but we wanted mission-aligned people who understand about the long term.”

The company has seen explosive growth since its last funding round in mid-2013, with monthly global unique user numbers rising from 35 million to 80 million.

Rattray said the rate of successful petitions put on Change.org (“the primary metric of success we use is victories”) has surged from one win every five hours a year ago to almost one win per hour.

He added that the funds would be used to invest in areas including mobile - half of all users of Change.org do so via a mobile device - and improving the ability for users to build support for very localised campaigns.

“I’m most excited about the local opportunity, we don’t do geo-local, which will enable people to take action in their immediate area on things such as food or school campaigns,” said Rattray.

“To date engagement and participation has been far away, remote physically, with big successful campaigns. The most effective way of engaging a broad swath of a local populations is not a small number of massive campaigns but a massive number of small campaigns.”

Another focus will be to build a tool to allow elected government officials or business leaders to directly engage with users of Change.org.

At the moment it is possible for this to happen “manually”, with Change.org contacting figures to facilitate a response to an issue.

This is what happened with deputy prime minister Nick Clegg who responded to 200,000-plus people involved in a petition on Change.org about parents who were arrested after removing their son with cancer from a hospital ward.

“We want to build a tool set to enable officials at all levels of government and in business to allow then to directly engage with citizens or consumers through the platform,” Rattray said. “At the moment we do it manually, we reach out, I’m excited about doing it at scale. We don’t just want consumers to be able to petition, we want businesses and officials to be able to respond.”

Rattray admitted that Change.org, which has 18 offices worldwide and about 200 staff, is not profitable but covers most of its costs from ad revenue.

“We are not focussed specifically on profitability but on continuing the trend of revenue growth and outside funding from investors. We have a higher level of revenues covering costs than most early and even mid-stage start-ups.”

In total the latest round of funding includes 25 investors.

Notable UK victories for Change.org petitions include Caroline Criado Perez’s campaign to keep a historic female figure on British banknotes.

Fahma Mohamed’s 250,000 strong petition calling on Michael Gove to write to headteachers in the UK about female genital mutilation.