Is this legal?

Yes. Our site counts as permitted third party campaigning within the terms of the Political Parties, Elections and Referendums Act. As our costs are well below £20,000 (in fact closer to £20) we are not required to register with the Electoral Commission. On the legality of vote swapping, Gerald Shamash of law firm Steel & Shamash told the Independent: “I can’t see that there would be any breach of electoral law. It’s a political decision for both parties: how best can we maximise our vote?”

Can I see who I am swapping with?

You will be sent the first name and constituency of the person you've swapped with. To ensure there are roughly equal numbers on each side we operate a waiting list on the side that is ahead until numbers on the other side have caught up.

Can you put me in touch with my swapper?

No, we can only send your their first name and constituency. There are other services available – such as Swap My Vote – that allow you to contact your swapper. (However VoteSwap is the only vote swapping website aimed at progressive voters; other services are also open to Tories, UKIP, etc.)

Can I can specify which constituency I'd like my match to vote in?

No. Our swaps are allocated in chronological order: our first Labour swapper with our first Green swapper, and so on. To see how we divide up seats, take a look at Vital Statistics.

I'm a Green voter in a Labour target seat, but I only want to swap with a Labour voter in a Green target seat. Why can't I do that?

Our objective is to minimise the number of Tory MPs. There are many seats that Labour can realistically win if Green supporters swap their votes. But they need voters with which to swap. If we only considered swaps from the smaller number of Green target seats then there would be very few Labour voters for Greens to swap with. And several of the Green target seats are battles between Labour and Green, so it is unlikely that Labour voters would want to swap.

While this site is neutral between Labour and Green (apart from in Brighton Pavilion where we call for a vote for Caroline Lucas to ensure a Green voice in parliament), we recognise the reality that there are more seats that Labour can win. VoteSwap gives Green voters in marginal seats the chance to vote Labour knowing that someone else will vote Green, thus keeping the Green share of the vote the same. In return Labour voters in safe seats can swap their vote knowing, perhaps for the first time, that their vote has made a difference.

Can you guarantee that my vote will be swapped?

No. We are absolutely honest about this. There are no guarantees here. People may not honour their pledge. People may adapt false identities. People may try to game the site. We are relying on the honesty and shared values of progressive voters. In any case partisans for one party would be much better off actively campaigning for their own party. We do however keep a wary eye on any suspicious behaviour, and delete anything that looks like spam.

Are you not playing dangerous games with the election result?

We are certainly trying to influence the results of certain seats and therefore the election, to stop the Tories from getting into power. That is our explicit political agenda. Our view is that first-past-the-post, particularly in an election when so many parties are getting a significant share of the vote, can produce results that are badly out of line with voter preferences. Swapping is better than ordinary tactical voting as it does not change the share of the vote nationally, but stops the progressive vote being split locally.

We are cautious about the advice we give in those seats, consulting a range of polls and forecasts. We are open to making changes when we are notified of errors, or where polling situations change in constituencies. And if you think we have got it wrong for a seat, then you do not have to follow our advice.

You’ve got my constituency wrong. What are you going do about it?

We are a small volunteer team that does not have local knowledge of every seat, and at every election there are always one or two constituencies that buck national trends. But we have adjusted our seat advice when we have had good local information put to us or we have made a mistake.

We initially attempted to divide every constituency into either a Labour target, a Green target, a safe seat or exceptional in some way (eg a Lib Dem-held seat). We now recognise that there is a further category of seat between target and safe for Labour. These may be ones that Labour is very likely to hold but without a huge majority, or one where Labour is mounting a strong challenge and could win in the longer term. We recognise that neither Green nor Labour voters will want to swap in those seats - they are not marginal enough to attract Green swappers, but Labour supporters will still want to back their own party rather than swap.

On the other hand some people who disagree with our approach (as is their absolute right) have tried to argue that Labour or Green have frankly unrealistic chances in particular constituencies. We understand why local activists are attached to their own candidates and parties, but while we celebrate that activism and commitment our sole objective is minimising the chances of a Conservative-led government in 2015.

Is this a trick by Labour supporters to get Green votes?

No. We are neutral between Green and Labour where both are in contention. For example in Lib Dem-held Cambridge, many observers think that Labour has a good chance. However we also recognise that this is an official Green target and therefore do not advocate a swap. In the majority of Green target seats we suggest Labour supporters vote Green and swap their vote with a Green supporter in a Labour target.

The one seat where we are not neutral is Brighton Pavilion where we think people should vote for Caroline Lucas, despite it being a Labour target. This is because even the Labour supporters involved in this site see the value of having a Green voice in Parliament, and think that Labour would be better off fighting in the many Tory-held marginals in and around Brighton. Of course Labour supporters in Brighton Pavilion are free to disagree, just as Green voters are free to disagree with us in knife-edge Labour targets. This site is just as much about providing the information that people need to make up their own minds as it is about vote swapping.

So is this a trick by Greens to get Labour supporters to vote Green?

No. In the vast majority of seats that experts have identified as ones in which a strong Green vote could stop Labour winning we are advocating Green voters swap so that they vote Labour. If we get enough swaps the benefit to Labour in their target seats is obvious, just as the Greens do not suffer a fall in their national total if some Green voters in Labour targets decided simply to switch to Labour to vote tactically.

Does the Green Party or the Labour Party endorse this site?

No. Not surprisingly, both parties think everybody should vote for them wherever you live.

Why don’t you include the Liberal Democrats?

In some seats a Lib Dem vote may be the most effective way to stop a Tory MP. We recognise that some progressive voters will want to vote Lib-Dem tactically in such seats. Our information can help people decide that (and we are currently updating that to point out when a seat is a Tory-Lib Dem battleground). But we also recognise that others will not want to vote Lib Dem after the coalition, or when the Lib Dems refuse to rule out another coalition with the Conservatives. We are therefore neutral on this and not facilitating a vote swap to help the Lib Dems. We recognise that people will have different views about how best for progressives to vote in such seats.

Are more Labour supporters or Green supporters offering to swap – and why?

At the moment we have more Labour supporters offering to vote Green in return for a swap. This is because there are both more Labour than Green voters nationally, and more safe constituencies than marginals. Contrast this with the numbers of Green voters living in the relatively small number of Labour target seats. When we get too many people offering to swap in one direction, we explain that they have been added to a waiting list and we will notify them if and when we find a match.

Why don't you cover Scotland, Wales or Northern Ireland?

VoteSwap is focused on swapping votes between Labour and Green supporters only. This simple model works in many constituencies in England, but is too limited for Scotland and Wales as it doesn't allow for the presence of the SNP or Plaid Cymru. This is truer still in Northern Ireland, where there is a different set of political parties.

Who are you?

Take a look at About us.

Who funds you?

We’re an unfunded volunteer project. The only thing that has been spent on VoteSwap is our time researching and building the website, and a little bit of money some of us have chipped in to host the website.