At the front of a packed auditorium, a young woman is speaking eloquent English in an Argentinian accent. She's telling her audience about 19th-century politics and explaining how the phrase "no taxation without representation" came to be coined. She isn't a university lecturer, and her subject isn't history. Her name is Pia Mancini, a technology revolutionary who is demanding an end to democracy as we know it.

"We are 21st-century citizens doing our best to interact with institutions established in the 19th-century, based on information technology from the 15th century," she says to a crowd of nodding heads in the audience of her recent TED talk.

The increasingly outdated nature of our voting system is something that hasn't escaped officials and campaigners in the UK. The Speaker's Commission on Digital Democracy recommended in January that online voting should be in place for the 2020 general election, while a report published earlier this month by the campaign group WebRoots Democracy found that this would boost the election turnout by nine million voters (as well as saving taxpayers £12m per general election).

Online voting has its critics, who point to the security risks and problems with voter anonymity. But there are other groups who aren't waiting for across-the-board support, and are instead using technology to make a difference at a grassroots level. Across the world, "hactivists" are trying to reboot democracy from the bottom up, building inclusive, interactive voting systems in the shape of apps.

One of these is DemocracyOS, an app and online platform developed three years ago in Argentina by a group of hackers and political scientists, including Pia Mancini. "We started DemocracyOS as an open-source free software application," says the group's president, Santiago Siri, from his temporary base in New York. "It allows you to get informed, debate and then vote online on the issues that concern you as a citizen. It's an application for the governance of all sorts of organisations – small ones such as the administration of a building, or large organisations like the city of Buenos Aires."

It was the Argentine capital where the platform was first rolled out in 2012 alongside a political group, the Net Party, which is committed to policies voted for on the DemocracyOS app. Although the Net Party didn't win any seats in its first election in 2013, the app was trialled by the Argentine Congress where it had some remarkable successes. "We got almost all political groups on board," says Mancini, DemocrayOS's executive director.

"They presented a total of 16 bills and the three ones that received the most votes were discussed by citizens." This led to the adoption of a proposal from the Workers' Party to improve the pay and working conditions of nurses in state hospitals. "The nurses' project only got in congress after DemocracyOS," said Mancini. "It was something that wasn't on the radar of the media at all, so it was a great experience."

Since 2013, more than 300 proposals have been discussed and voted on by the citizens of Buenos Aires via the app. Users simply register, find a proposal that they are interested in – or create their own – read the information and debate it, then cast their vote. Votes can even be delegated to someone else who is more qualified, thus providing a weighting system in favour of knowledge and expertise.

And because the coding which the platform is based on is open source – essentially not copyrighted – anyone can use the technology for free and develop for their own needs, regardless of the geographical and political landscape. It is this flexibility that has seen the platform spread beyond Argentina, to countries such as Spain where it has been adopted by the increasingly popular left-wing party, Podemos, and by the federal government of Mexico, which is using it to discuss its open-data policy.

It might even reach UK shores soon. Chris Pane is a 26-year-old student, entrepreneur and Green Party member living in Bournemouth. Pane had been thinking about his own idea for a system of digital democracy for the past few years, since he first heard about DemocracyOS. He decided to contact Pia Mancini directly and she put him in touch with British model-turned-entrepreneur Lily Cole. Cole held a fringe event at the Green Party's 2015 spring conference in Liverpool earlier this month about digital democracy and Pane found himself sitting next to Cole and Green Party leader, Natalie Bennett, addressing a room full of interested members on the possibility of adopting a system such as DemocracyOS for internal policy voting.

The concept was well received and now Pane is working on the process of getting it adopted as party policy, ready for a vote at the autumn conference. "The current system is a bottom-up process," explains Pane, "which is fantastic but it's only limited to conferences so it's only the capacity of the room, which was 1,350 at the last conference. We've got thousands of other members that weren't able to turn up, so this software gives them the option to be included."

The DemocracyOS app was developed by hackers and political scientists

As a hard-up student, Pane's own concept of a digital democracy platform, which he calls "Balance", was without coders to create it and without funding to back it, which is where the beauty of open-source software comes in. DemocracyOS can provide him, and the Green Party, with a ready-made platform that can be tweaked to their individual needs and which, more importantly, is completely free. "There's no point in trying to reinvent the wheel," he says, "when I can use DemocracyOS and champion this platform in the UK faster."

DemocracyOS isn't the only platform that would-be reformers such as Pane can choose from. Around the world there are a surprising number of applications in various stages of development. One political party in Germany, the Pirate Party, uses a similar platform, called Liquid Democracy, for its policy-making decisions, and a host of other programmers across the world are having a go at their own systems, including two separate platforms based on the technology behind the internet-based currency BitCoin called, unsurprisingly, BitVote.

It is the very popularity of such projects that is one of their main drawbacks, according to one BitVote developer, Phoebus Giannopoulos. "Right now we have about 30 different approaches," he said, "which are not in communication with each other or coming to some forum which could speed up these kinds of software."

Despite, or perhaps because of this, developers and activists around the world are pushing on with their plans, generating a groundswell of momentum for grassroots, open-source, online democracy. DemocracyOS is riding the crest of this wave with Mancini's TED talk and a recent appearance on BBC2's Newsnight. Santiago Siri and Pia Mancini were recently in the US where they spoke to representatives from New York city council and members of the US Congress about the potential of their app – a startling step up for the fledgling group. But this is a way of thinking that, by its very nature, aims big. "What we are fishing for," says Mancini, "is to use this media to build new institutions for a democracy of the 21st century. We're really trying to make an organisation that can build a democracy for the world."